Enhancing farmers’ enthusiasm for grain cultivation is crucial for ensuring national food security. This study uses survey data from 1,337 households across 24 counties in Jiangxi Province, measuring farmers’ enthusiasm for grain cultivation through their willingness to plant double-cropping rice. It analyzes the impact of agricultural socialization services on this enthusiasm and the underlying mechanisms. The findings are as follows: 1) Agricultural socialization services have a significant positive impact on farmers’ enthusiasm for grain cultivation, increasing their willingness to plant double-cropping rice. These services also significantly encourage single-cropping rice farmers to switch to double-cropping and support double-cropping farmers in continuing their practices. 2) The impact of agricultural socialization services on farmers" enthusiasm varies across different stages of the agricultural process, with services related to rice seedling raising, fertilization, and pesticide application having a particularly significant positive effect. 3) Mechanism analysis reveals that agricultural socialization services boost farmers’ enthusiasm by reducing labor input per unit, promoting the expansion of operational scale, and increasing rice yield. 4) Heterogeneity analysis indicates that these services primarily enhance the enthusiasm for grain cultivation among farmers in plain areas, those with lower land fragmentation, and those with higher digital literacy. Therefore, it is recommended to strengthen the agricultural socialization service system, focus on developing technology-intensive services, further reduce land fragmentation, and improve farmers’ digital literacy to enhance their enthusiasm for grain cultivation.