string strPass = @"D:\WinAutoTest\sanjiao.exe";

            Assembly assebly = Assembly.LoadFrom(strPass);

            Module module = assebly.ManifestModule;

            Type[] types = module.GetTypes();

            Type tpForm = typeof(Form);

            foreach (Type type in types)

            {

                if (type.IsSubclassOf(tpForm))

                {

                    MessageBox.Show(type.FullName);

                }

            }