今天整了一天时间，终于可以取到accountExpires

并转换为DateTime时间。

private long LongFromLargeInteger(object largeInteger)
    {
        System.Type type = largeInteger.GetType();
        int highPart = (int)type.InvokeMember("HighPart", System.Reflection.BindingFlags.GetProperty, null, largeInteger, null);
        int lowPart = (int)type.InvokeMember("LowPart", System.Reflection.BindingFlags.GetProperty, null, largeInteger, null);

return (long)highPart << 32 | (uint)lowPart;
    }
    DateTime LargeIntToDateTime(ActiveDs.LargeInteger li)
    {
        long lTime;
        lTime = (long)li.HighPart;
        lTime <<= 32;
        lTime |= (uint)li.LowPart;
        return System.DateTime.FromFileTime(lTime);
    }

ActiveDs.LargeInteger pwdLastSet = child.Properties["pwdLastSet"].Value as ActiveDs.LargeInteger;

if ((accountExpires.HighPart == Int32.MaxValue) && (accountExpires.LowPart == -1))
{

//有效时间

//时间总是相差1天，所以我加了一个 -1

String dt=LargeIntToDateTime(accountExpires).AddDays(-1).ToString()
}

largeInteger 找不能命名空间了吧？

引用com 组件：Active DS Type Library

接下来设置这个属性，就比较方便了

using System.Reflection;

// Get the native object.
Type type = usr.NativeObject.GetType();
Object adsNative = usr.NativeObject;

// Use the Type.InvokeMember method to invoke the
// AccountExpirationDate property setter.
type.InvokeMember(
    "AccountExpirationDate",
    BindingFlags.SetProperty,
    null,
    adsNative,
    new object[]{"12/29/2004"});

// Commit the changes.
usr.CommitChanges();

The following C# example shows how to use the InvokeSet method to set the value of the IADsUser.AccountExpirationDate property.

// Use the DirectoryEntry.InvokeSet method to invoke the
// AccountExpirationDate property setter.
usr.InvokeSet(
    "AccountExpirationDate",
    new object[] {new DateTime(2005, 12, 29)});

// Commit the changes.
usr.CommitChanges();