Compressor is the important mechanism of baler. This paper uses the virtual prototyping technology. It analyzes the Function of Compression device in 9KG-350 high density baler and the three-dimensional digital model of compression device is obtained based on UG package .Then the model is put into ADAMS, and a kinematical analysis is performed. Through the simulation, the whole kinematical process is reflected, gaining the relative kinematical curves of Compression device as well. The results can be help in d...