This study investigates how environmental regulations and social norms affect farmers’ chemical fertilizer reduction behaviors (CFRBs) and investigates the mediating role played by social norms and the moderating role played by social networks. As the analysis tool, a structural equation model is employed to analyze the data collected from a questionnaire survey with 402 valid samples of Chinese citrus growers. This study reveals that (1) environmental regulations and social norms have a significant effect on farmers’ CFRBs; (2) injunctive social norms are a partial mediator of the relationship between incentive-based environmental regulations and farmers’ CFRBs; (3) social networks play a positive moderating role in the relationship between injunctive social norms and farmers’ CFRBs; and (4) large-scale farmers’ CFRBs are more susceptible to the impact of environmental regulations and social norms than small-scale farmers. The result of this study provides a significant scientific foundation for the Chinese agricultural sector to develop policies to combat soil pollution in agriculture.