Agricultural mechanization has played an important role in promoting non-agricultural employment for rural labor and increasing farmers" income. However, current literature has different empirical conclusions on the relationship between agricultural mechanization and production efficiency. Based on the panel data of National Fixed-site Rural Survey (NFRS) conducted by the Ministry of Agriculture of China from 2003 to 2016, this study adopts the stochastic frontier production function model to evaluate the effect of agricultural mechanization on aggregated grain production efficiency of farmers. To begin with, the more the farmers employ agricultural machines, the better the technical efficiency of farmers" total grain production will be. Moreover, the marginal effect of agricultural machinery expenditure has decreased in recent years. Last but not the least, the technical efficiency of farmers holding agricultural machine is higher than that of farmers without agricultural machine. The future path of agricultural technology and system should be “making land infrastructure and institutions suit agricultural machinery”. Agricultural infrastructure construction, such as farmland renovation, should adapt to the development of agricultural mechanization. Scale economy could be realization by agricultural mechanization step. By so doing, the land could be centralized in production and management.