Abstract: Agricultural socialization services serve as an important means for small-scale farms to integrate into modern agriculture, and they are of great significance for accelerating the entry of small-scale farms into the process of agricultural green development. Considering that farmers are both the suppliers and demanders of food, the differences in their implicit objective functions will affect the principal-agent relationship and restrict the power of service providers to make decisions on the usage of pesticides and fertilizers. Based on the 2020 China Rural Revitalization Comprehensive Survey Data (CRRS), this study analyzed the key factors causing changes in the principal-agent relationship due to farmers’ “dual identity”. Results show that: 1) agricultural socialization services significantly reduce the use of pesticides and fertilizers. If farmers participate in the operation process, it will inhibit their positive effect of reducing pesticide use, but has no significant impacts on the use of fertilizers; 2) sales decisions inhibit the positive effect of agricultural socialization services in reducing the use of pesticides and fertilizers; 3) health literacy strengthens the inhibitory effect of agricultural socialization services on the use of pesticides and fertilizers, but environmental literacy only strengthens the inhibitory effect of agricultural socialization services on the use of pesticides; and 4) agricultural socialization services can significantly reduce the use of pesticides and fertilizers for wheat and corn, and the inhibitory effect on fertilizer use is stronger in non-grain-producing areas. Therefore, it is recommended to increase the promotion of agricultural socialization services, strengthen farmers’ ecological awareness, and establish a reasonable incentive compatibility mechanism.