namespace DllTest
{
    abstract class Base
    {
        public abstract void Run();
    }
    class PBase : Base
    {
        public override void Run()
        {
            MessageBox.Show("Overrided Run!");
        }
    }
}

public Form1()
{
            InitializeComponent();
            AssemblyNameProxy ap = new AssemblyNameProxy();
            AssemblyName myAssemblyName = ap.GetAssemblyName("DLLTest.dll");//获取程序名
            Assembly assembly = Assembly.Load(myAssemblyName); //手动加载程序集   
            Type type = assembly.GetType("DllTest.PBase"); //获取程序集中的类型
            object obj = Activator.CreateInstance(type);//创建对象实例
            (obj as DllTest.PBase).Run();
 }