Abstract: Low-carbon agriculture is one of the important ways for China to achieve the “double carbon” goal, and agricultural socialization services provide a new way for the development of low-carbon agriculture. Based on the panel data of 13 provinces, autonomous regions and municipalities in China’ s main grain-producing areas from 2003 to 2022, this paper used the entropy method to measure the level of agricultural socialized services, analyzed the impact and mechanism of agricultural socialized service level on agricultural carbon emission intensity by using the two-way fixed-effect model, and then used the mediating effect model to explore the indirect effects of agricultural operation scale and fertilizer application intensity as mediating variables, and finally conducted heterogeneity analysis. The results showed that, agricultural socialized services could significantly reduce agricultural carbon emission intensity in major grain producing areas. Agricultural socialization services reduced agricultural carbon emissions through the mediating effect of agricultural operation scale and fertilizer application intensity. The results of heterogeneity showed that there were regional differences in the impact of agricultural socialization services on agricultural carbon emissions, and the impacts of different dimensions of agricultural socialization services were also different. Based on this, it was recommended to advance the implementation of the policy of agricultural socialized services, promote regional coordinated development, increase publicity and education, driving the digital transformation of agriculture, promote the progress of national agricultural socialized services, and help realize the low-carbon transformation of agriculture as soon as possible.