Abstract: Profit Portion estimation for the mechanization in plant products industry is useful to understand the development level, potential, trend of agricultural mechanization for government decision making and it is also an answer to how to estimate the single factor's influence on an complicated economic system. So far, there is no standard and easy method estimating the profit. Based on the idea of “with and without project comparison method” in project analysis, a direct method was developed to estimate the profit portion of mechanization in the plant products industry by a comparison between mechanization and no mechanization in the plant products industry. As a case study, the mechanization profit portion in China's plant products industry was estimated in this paper, and the estimated value is 18.33%.