Because of the wide use in the aerospace, oil, mining and other fields, the grinding method of cemented carbide balls has been a research hot spot. Evaluating the lapping uniformity is a main mean to study the processing method of cemented carbide balls. In order to improve the accuracy of grinding homogeneity evaluation method, considering the influence of the original surface topography and grinding pressure, the material removal equation during ball lapping process is deduced by single factor test using MATLAB software, and a quantitative evaluation method and a simulation model of lapping uniformity using the eccentric lapping method with two rotatable lapping plates are proposed in this paper. Moreover,the orthogonal experiment is used to verify the proposed method and the results show that the method is effective to predict the effect of grinding pressure, rotating speed of upper and lower plates on the grinding accuracy.