这是因为解串器不知道如何处理子对象。你有JS这是什么：

It's because the deserializer doesn't know how to handle the sub-object. What you have in JS is this:

var x = {
  'property1' : 'string',
  'property2' : 'string',
  'property3' : { p1: 'string', p2: 'string', p3: 'string' },
};

不具有地图的东西有效在C＃：

which doesn't have a map to something valid in C#:

HashTable h = new HashTable();
h.Add("property1", "string");
h.Add("property2", "string");
h.Add("property3", ???);

该???是因为没有这里定义的类型，所以怎么会解串器知道在你的JS重新presents匿名对象吗？

The ??? is because there's no type defined here, so how would the deserializer know what the anonymous object in your JS represents?

修改

有没有办法做你试图在这里完成的。你需要让你的对象类型。例如，定义这样的类：

There is no way to do what you're trying to accomplish here. You'll need to make your object typed. For example, defining your class like this:

class Foo{
  string property1 { get; set; } 
  string property2 { get; set; }
  Bar property3 { get; set; } // "Bar" would describe your sub-object
}

class Bar{
  string p1 { get; set; }
  string p2 { get; set; }
  string p3 { get; set; }
}

...或者诸如此类的话。

...or something to that effect.