In order to analyze the dynamic behavior of luffing mechanism, Pro/E was used to make the threedimensional solid model of JVR300Z rotary drill rig, the model was imported into software ADAMS to add restriction and drive.The simulation for the luffing mechanism was made. The cylinder load roles were gotten: the changing of gravity center has a certain impact on the luffing mechanism, especially when the drill pipe on the mast is converted from static friction to dynamic friction, the mast luffing cylinder and the parallelogram structure of luffing mechanism get heavy impact force. The impact force is an important basis to check luffing mechanism strength and to ensure the design of mechanical structure can meet the requirements for usage.