The performance simulation of a small-scale corn harvester for hilly area using ADAMS was presented. The 3-D parametric model of the corn harvester was established with Pro/E. Then, the model was put into UG to conduct Boolean operation to reduce the amount of constrains. Consequently, the model was simplified and workload was cut down. The preprocessed model was import to the ADAMS environment to build the virtual prototype model. A comparison between the simulation and the road test verified that the virtual prototype model met the requirements of virtual experiment. The extreme roll angle and maximum climbing slope were obtained by ADAMS simulation to avoid hazardous vehicle test on sloping area. In addition, the terrain trafficability of the corn harvester on the weak ground was analyzed with cone index.