The function income dist ribution means that the productive achievements are dist ributed acco rding to the role or con tribu tion made by the various productive factors in social production. Whether it is reasonable or not directly affects the optimal allocation of the productive factors. The paper has m adem easurement on the revenue shares by labor and capital in nationalincome since the econom ic reform in ou rcountry, and analyzed the reason for the arising of labor share by economet ricmodel.