Abstract: Mechatronics system design requires mutli technical integrated unified modeling ＆ simulation Multi body system dynamics is a difficulty Traditionally through multi body domain specific software packet, the DAE is generated, which is then converted to the uniform modeling language embedded in the integrated environment In this paper, a conservative system is modeled through generalized Kichhoff network theory Adopting port based integrated component, the hybrid system is modeled based on VHDL AMS For better integration, a GKN model of multi body system dynamics is constructed by selecting the reference frame as a terminal Therefore the multi body system is integrated into the unified modeling environment based on VHDL AMS Finally, a detailed demonstration example is given, and the simulation result is well in accordance with the theory