Abstract: Based on the characteristic that tractor front wheel and rear wheel have generally different diameters, a determination method of the height of tractor mass center on the basis of mass-response method was brought out and the corresponding theoretic calculating model was developed. By comparing with national standard of road vehicles with two axles, it was found that the theoretic calculating model given in the standard was only a special case of the model presented in this paper. This method was used for determining the mass center of the CF650 tractor produced by Jiangsu Changfa Groups and the maximum relative error was 0.34%. The result showed that this method for determining the height of mass center of tractor could satisfy the precision requirement of engineering.