This paper researches the behavior of using soil testing formula fertilizer at farms of different sizes. The study develops a probit model based on peasant household survey data from 11 grain production areas. The results prove that: First, obvious differences exist in the distribution of formula fertilizer use ratio among farms of different sizes; large-scale farmers are the highest, small-scale farmers are the lowest. Second, from external factors, the increased yield of corn, soil testing services, and information dissemination, it is clear that training has a significant positive effect on farmers' use behavior; the influence of soil testing services is the greatest. Third the higher the degree of organization, marketization and scale of a farm, the more likely the farmer is to use soil testing formula fertilizer. Policy recommendations are made on the basis of the empirical research presented in this paper.