I have Done Few Changes To Your Code..
Try This..
<script src="//ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script type="text/javascript">
function GetDateTime(json1) {
$.ajax
({
type: "POST",
url: "Default.aspx/GetServerDateTime",
data: JSON.stringify(json1),
contentType: 'application/json; charset=utf-8',
dataType: 'json',
success: function (result) {
alert(result.d);
},
error: function (err) {
alert("Ajax Error");
}
});
}
</script>
protected void Button1_Click(object sender, EventArgs e)
{
string json1 = "{'one':'1','two':'2','three':'3'}";
ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "scr", "Javascript:GetDateTime(" + json1 + ");", true);
}
[WebMethod]
public static string GetServerDateTime(string one, string two, string three)
{
return Convert.ToString(DateTime.Now.ToString() + " " + one + two + three);
}