This paper introduces the virtual prototyping technology(VP) and its application briefly,explains the significance of implementing the VP in the engineering machinery enterprises,and discusses about the key technology among them. By taking WA4701 wheel loader as an example,the paper expounds the application of the VP to the loader’s working design.Through using the proe software,the paper also elaborates the kinematical modeling of the loader’s working,then analyses the intensities of the lift arm,and solves the stress of the lift arm with lean operation,so as to offer the scientific basis for the design of the loader’s working to shorten design cycle,to reduce the material quantity of the lift arm and to improve the competitiveness of the products.