Multi-platform software development is a difficult problem frequently met in engineering practice. In practice, we adopt the method of GUI encapsulation in establishing one layer of interface called the interface abstracts layer. In transporting the whole program, the only thing to do is to revise this layer of interface, which only needs the least work load, thus better solving the problem of program transportability. On the Alpha work station, by taking the exploitation of GUI interface with Motif for example, the development in message loop, base widget of GUI interface and Event Callback is realized from Alpha-Unix's platform to PC-window's platform, and a good practical effect is obtained.