Abstract: Agricultural productive services are an important mechanism to promote the transformation of agricultural green production. Although the existing literature has widely explored the relationship between agricultural productive services and pesticide input, there is still a lack of empirical research on the mechanism of opportunistic behavior. Based on the data of the 2020 China Rural Revitalization Survey (CRRS), this paper explores the impact of agricultural productive services on pesticide reduction and its transmission mechanism. The study found that farmers' purchase of pesticide application services significantly promoted the reduction of pesticide application, among which the embedding of advanced technologies and the improvement of organizational level were the main transmission paths. The reliability of the conclusion was verified by the instrumental variable method and a series of robustness tests. Heterogeneity analysis showed that compared with wheat and corn growers, rice growers had a more significant reduction effect when purchasing pesticide application services. Compared with large-scale farmers, the pesticide reduction effect of small farmers purchasing pesticide application services was not significant, which was mainly due to the opportunistic behavior in the pesticide application service market. Improving the scale of rural land management and the supply of productive services can improve the competitiveness of the service market in the region, effectively reduce the probability of service opportunistic behavior, and promote the reduction of pesticides by small farmers. The policy implication of this article is that we need to focus on opportunistic behavior when developing the agricultural productive service market, and optimize the service market environment by improving the level of large-scale land management and service support, so as to provide important driving force for the green transformation of agriculture.