With the change of agricultural endowment and induced technological progress in China,farm households transform inputs structure accordingly,which contributes to the growth of labor productivity.This paper constructs elastic coefficient of input factor allocation ratio affecting labor productivity and examines the effect of factor allocation ratio change on labor productivity of crops with maize as the example based on the expanded cobb-douglas production function.The results show that:factor allocation structure adjustment enhances maize’s labor productivity because technical equipment allocated to unit labor has been improved significantly through increasing the use of fertilizer and machinery and reducing the labor.At the national level,the elasticity coefficient of fertilizer-labor ratio is significantly positive having most remarkable effect on maize’s labor productivity which can also be improved by increasing the seed-labor ratio and machinery-labor ratio.At the provincial level,the elasticity coefficient of fertilizer-labor ratio,seed-labor ratio,machinery-labor ratio and pesticide-labor ratio are significantly positive in North China.The elasticity coefficient of pesticide-labor ratio is negative in Northeast China and the elasticity coefficient of machinery-labor ratio isn’t significant in Southwest China.Compared with labor-saving factor,land-saving factor has more significant effect on maize’s labor productivity,which applies to both national and provincial level.The policy implication is that on the one hand we should unswervingly promote the transfer of labor force employment,on the other hand,we should improve the quality and utilization efficiency of input factors and optimize the structure of factor allocation,especially pay attention to the matching of the inputs factor,the integration of technical equipment and the development of agricultural socialized services.