The machine is subjected to the inertial effect produced by its inherent mass and moment of inertia from working parts besides external load during operation processes. In the traditional methods of machinery dynamical balancing, the influences of the friction, gravity and the external loads (working load) haven’t been considered. In this paper, the external loading has become an important factor in dynamical balancing problems. Based on Virtual Prototyping (VP) technology, we studied the effect of loading to dynamical balancing when taking several kinds of targets as the optimized goal. The conclusion has significance value for practical application and offers some references to dynamic balance of other mechanisms.