Abstract: Clarifying the mechanism by which rural population aging affects green agricultural development is of great significance for accelerating the green transformation of agriculture in China. Based on the panel data of 31 provinces (excluding Hong Kong, Macao, and Taiwan of China) in China from 2003 to 2020, this study measured the level of agricultural green development in China and empirically analyzed the influence mechanism of rural population aging on agricultural green development using the fixed- and moderating-effect models. The results show that: 1) The level of agricultural green development in China is consistently enhancing; however, inter-provincial disparities demonstrate an expanding tendency, and the dynamic adjustment of regional agricultural green development is conspicuous, featuring an overall unbalanced development. 2) Rural population aging significantly inhibits green agricultural development and this inhibitory effect is more prominent in low-aging regions. According to the fractal heterogeneity test, rural population aging inhibits resource conservation and economic effects, plays a significant role in promoting environmental friendliness, but has no effect on ecological conservation. In general, the negative effects of aging on the rural population outweigh the promotional effects, thereby inhibiting green agricultural development. 3) The impact of rural population aging on agricultural green development exhibits a U-shaped nonlinear relationship, with an inflection point of 0.16. Because most of the sample is distributed to the left of this inflection point, the marginal impact is predominantly negative. 4) According to the development of China’s agricultural socialized services, agricultural socialized services can notably enhance the level of agricultural green development. Meanwhile, it can exert a regulatory function in the process by which rural population aging influences green agricultural development; that is, it can effectively mitigate the inhibitory impact of rural population aging on green agricultural development. Therefore, local policies should be adopted to promote green agricultural development and constantly narrow the development differences between regions. Efforts should be made to enhance the human capital accumulation effect on elderly farmers, vigorously cultivate new professional farmers, support and encourage all types of new business entities to accelerate the supply of socialized agricultural services, actively guide elderly farmers to integrate into the social service system in an orderly manner, realize the organic connection between elderly farmers and modern agriculture, and promote green agricultural production.