In this paper,the relationship between the development of agricultural machinery service and the efficiency of grain production in China is studied by using the two-step method. Based on the panel data of grain production input and output in 31 provinces of China from 2004 to 2016,this paper calculated the technical change,technical efficiency and total factor productivity of grain production in China by using variable coefficient stochastic frontier analysis method,and then constructed the OLS regression model of agricultural machinery service development affecting grain production efficiency.The results show that:(1)There are obvious differences in input factor output elasticity and technical efficiency of grain production in 31 provinces,and the change of grain technology was the most obvious in 2008,and the growth of total factor productivity of grain reached as high as 5% in 2008. (2)The development of agricultural machinery service has a significant promoting effect on the growth rate of grain TFP after 2008,indicating that the effect of agricultural machinery service on grain TFP has a certain lag effect. (3)The development of agricultural machinery service has a substitute relationship with labor output elasticity yet a complementary relationship with chemical fertilizer and mechanical output elasticity. The results also show that the mechanization of wheat is the highest among the three major grain crops yet the mechanization of rice and corn still needs to be improved.