Abstract: Based on the survey data of 425 large-scale farmers in major grain producing areas of Anhui and Shandong provinces, this paper used stochastic frontier analysis to measure the fertilizer use efficiency of large-scale farmers, and built endogenous switching regression model to empirically analyze the impact of adoption of soil testing and formulated fertilization technology on fertilizer use efficiency by large-scale farmers. The results showed that: (1) The average fertilizer use efficiency of large-scale farmers is 0.300, and the input redundancy is serious. (2) The adoption behaviour of soil testing and fertilizer application technology by large-scale farmers has significant positive bias. Large-scale farmers with higher fertilizer use efficiency we more likely to adopt soil testing and formulated fertilization technology. Besides, factors such as age, education, agricultural technology training, village cadres family, management scale, land ownership, land leveling have have significant impact on the adoption behaviour of soil testing and fertilizer application technology by large-scale farmers. (3) The adoption of soil testing and fertilizer application technology significantly improves the fertilizer use efficiency by large-scale farmers. Under the counterfactual framework, the adoption of soil testing and formulated fertilization technology increases the efficiency of fertilizer use by 0.041, with an increase of 13.95%. However, this effect is also heterogeneous in the case of the difference in the degree of side-work and the labor-land relationship. The improvement effect of soil testing and fertilizer application technology on fertilizer use efficiency is more obvious for large-scale farmers who take agriculture as their business and adapt labor to land.