Abstract: At present, machinery CAD is going to be integrative CAD/CAM/CAE, and the kinematics dynamics analysis software for machinery system is one of the necessary supporting softwares of integrative CAD/CAM/CAE. An interactive, problem-oriented, general machinery computer-aided design system GMCADS (General Machinery Computer - Aided Design System) is developed by using the basic theory of dynamics of multi - rigid - body system. the analytic principle and graphic display technique of GMCADS are introduced with the application examples given.