diff --git a/org.tinygroup.tinyscript/src/test/resources/example/date.ts b/org.tinygroup.tinyscript/src/test/resources/example/date.ts
index d4856b12e7017bac68d79dece1e1769672f85995..fd419cb147fc7f8f8e8d1c2114ac501fa6b5dd4c 100644
--- a/org.tinygroup.tinyscript/src/test/resources/example/date.ts
+++ b/org.tinygroup.tinyscript/src/test/resources/example/date.ts
@@ -8,8 +8,6 @@ println(dateName("WEEKDAY",date1));
 println(datePart("WEEK",date1,"monday"));
 println(dateTrunc("WEEKDAY",date1));
 println(day(date1));
-println(isDate("2017/11/30"));
-println(isDate("2017/11/30","yyyy/MM/dd"));
 println(makeDate(2010,10,1));
 println(makeDateTime(date2,time));
 println(month(date1));
@@ -17,4 +15,5 @@ println(year(date1));
 println(now());
 println(today());
 println(max(date1,date2));
-println(string(date1,"yyyy/MM/dd"));
\ No newline at end of file
+println(date1.string());
+println(date1.string("yyyy-MM-ss"));
\ No newline at end of file
diff --git a/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/expression/TypeConvertUtil.java b/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/expression/TypeConvertUtil.java
index 18b08a555629e394b2221772733e34384da189d1..fac60693eb35a40c5a461dc2244245118ba797a7 100644
--- a/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/expression/TypeConvertUtil.java
+++ b/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/expression/TypeConvertUtil.java
@@ -29,7 +29,6 @@ public final class TypeConvertUtil {
 		addTypeConvertProcessor(new FloatTypeConvertProcessor());
 		addTypeConvertProcessor(new DoubleTypeConvertProcessor());
 		addTypeConvertProcessor(new DateTypeConvertProcessor());
-		addTypeConvertProcessor(new StringTypeConvertProcessor());
 	}
 
 	/**
diff --git a/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/expression/typeconvert/StringTypeConvertProcessor.java b/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/expression/typeconvert/StringTypeConvertProcessor.java
deleted file mode 100644
index ea9019035e555586e718a66cde81dd20be918351..0000000000000000000000000000000000000000
--- a/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/expression/typeconvert/StringTypeConvertProcessor.java
+++ /dev/null
@@ -1,27 +0,0 @@
-package org.tinygroup.tinyscript.expression.typeconvert;
-
-import java.util.Date;
-
-import org.tinygroup.tinyscript.expression.TypeConvertProcessor;
-import org.tinygroup.tinyscript.function.date.DateUtil;
-
-public class StringTypeConvertProcessor implements TypeConvertProcessor {
-
-	@Override
-	public String getName() {
-		return "string";
-	}
-
-	@Override
-	public Object convert(Object... parameters) throws Exception {
-		if (parameters != null) {
-			if (parameters.length == 1) {
-				return DateUtil.dateToString((Date) parameters[0], null);
-			} else if (parameters.length == 2) {
-				return DateUtil.dateToString((Date) parameters[0], (String) parameters[1]);
-			}
-		}
-		return null;
-	}
-
-}
diff --git a/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/function/date/IsDateFunction.java b/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/function/date/DateToStringFunction.java
similarity index 72%
rename from org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/function/date/IsDateFunction.java
rename to org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/function/date/DateToStringFunction.java
index 56d4f067b1c5384a175f66a8b203df22726497d1..f147229865bda760e8dcb4fbbde98fc51a437f04 100644
--- a/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/function/date/IsDateFunction.java
+++ b/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/function/date/DateToStringFunction.java
@@ -1,6 +1,6 @@
 package org.tinygroup.tinyscript.function.date;
 
-import java.text.ParseException;
+import java.util.Date;
 
 import org.tinygroup.tinyscript.ScriptContext;
 import org.tinygroup.tinyscript.ScriptException;
@@ -9,11 +9,15 @@ import org.tinygroup.tinyscript.function.AbstractScriptFunction;
 import org.tinygroup.tinyscript.interpret.ResourceBundleUtil;
 import org.tinygroup.tinyscript.interpret.exception.NotMatchException;
 
-public class IsDateFunction extends AbstractScriptFunction {
+public class DateToStringFunction extends AbstractScriptFunction {
 
 	@Override
 	public String getNames() {
-		return "isDate";
+		return "string";
+	}
+
+	public String getBindingTypes() {
+		return "java.util.Date";
 	}
 
 	@Override
@@ -22,21 +26,17 @@ public class IsDateFunction extends AbstractScriptFunction {
 			if (parameters == null || parameters.length == 0) {
 				throw new ScriptException(ResourceBundleUtil.getDefaultMessage("function.parameter.empty", getNames()));
 			} else if (checkParameters(parameters, 1)) {
-				DateUtil.convertDateByString((String) parameters[0], null);
-				return true;
+				return DateUtil.dateToString((Date) parameters[0], null);
 			} else if (checkParameters(parameters, 2)) {
-				DateUtil.convertDateByString((String) parameters[0], (String) parameters[1]);
-				return true;
+				return DateUtil.dateToString((Date) parameters[0], (String) parameters[1]);
 			} else {
 				throw new NotMatchException(
 						ResourceBundleUtil.getDefaultMessage("function.parameter.error", getNames()));
 			}
-		} catch (ParseException e) {
-			return false;
 		} catch (ScriptException e) {
 			throw e;
 		} catch (Exception e) {
-			throw new ScriptException(ResourceBundleUtil.getDefaultMessage("function.run.error", getNames()), e);
+			throw new ScriptException(ResourceBundleUtil.getDefaultMessage("function.parameter.error", getNames()), e);
 		}
 	}
 
diff --git a/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/impl/DefaultScriptEngine.java b/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/impl/DefaultScriptEngine.java
index 0288d41c3b8fbacca8576d4f57e7705233d2cdd1..75e49138317d71979e57cae18b63792e3bc3da93 100644
--- a/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/impl/DefaultScriptEngine.java
+++ b/org.tinygroup.tinyscriptbase/src/main/java/org/tinygroup/tinyscript/impl/DefaultScriptEngine.java
@@ -81,7 +81,6 @@ public class DefaultScriptEngine extends AbstractScriptEngine {
 		addScriptFunction(new DatePartFunction());
 		addScriptFunction(new DateTruncFunction());
 		addScriptFunction(new DayFunction());
-		addScriptFunction(new IsDateFunction());
 		addScriptFunction(new MakeDateFunction());
 		addScriptFunction(new MakeDateTime());
 		addScriptFunction(new MonthFunction());
@@ -90,6 +89,7 @@ public class DefaultScriptEngine extends AbstractScriptEngine {
 		addScriptFunction(new YearFunction());
 		addScriptFunction(new EqualsDateFunction());
 		addScriptFunction(new DateDifferentFunction());
+		addScriptFunction(new DateToStringFunction());
 		addScriptFunction(new TypeConvertFunction());
 		addScriptFunction(new EvalScriptFunction());
 
diff --git a/org.tinygroup.tinyscriptbase/src/test/java/org/tinygroup/tinyscript/DateTest.java b/org.tinygroup.tinyscriptbase/src/test/java/org/tinygroup/tinyscript/DateTest.java
index c43315eeae93e441ab337dbce1ce61619cb4da78..5381596ba0cba094a431fd3c035e2717734c4977 100644
--- a/org.tinygroup.tinyscriptbase/src/test/java/org/tinygroup/tinyscript/DateTest.java
+++ b/org.tinygroup.tinyscriptbase/src/test/java/org/tinygroup/tinyscript/DateTest.java
@@ -51,7 +51,6 @@ public class DateTest extends TestCase {
 		assertEquals("tuesday", scriptEngine.execute("return dateName(\"WEEKDAY\",date1);", context));
 		assertEquals(44, scriptEngine.execute("return datePart(\"WEEK\",date1,\"monday\");", context));
 		assertNotNull(scriptEngine.execute("return dateTrunc(\"WEEKDAY\",date1);", context));
-		assertEquals(false, scriptEngine.execute("return isDate(\"2017/11/30\");"));
 
 	}