Polygon clipping is the important process in computer graphics applications. Clipping is also a complex algorithm. Many researches have been done at this time to find a better algorithm than the previous one.This research will analyze and implement one of the algorithms, which is Weiler Atherton, and then is compared with Sutherland Hodgeman algorithm, because Sutherland Hodgeman algorithm is well accepted in many applications. The implementation will use Borland Delphi as the programming language. The experiment shows that Weiler Atherton algorithm is slower than Sutherland Hodgeman algorithm, but the advantage is this algorithm can calculate the clipping process that creating more than one polygon. Another result, this algorithm like Sutherland Hodgeman, can only works on rectangle window clipping and cannot calculate the clipping process which the subject is complex polygon.