Abstract: Climate warming has become an immediate threat to mankind, Carbon emissions from agricultural production constitute one of the important sources of greenhouse gases. In this context, clarifying the logic of carbon productivity growth in agriculture is conducive to “maintaining growth” and “promoting emission reduction” from the source.On the basis of a the theoretical analysis of the effect mechanism of financial support for agriculture on agricultural carbon productivity, this paper calculates the agricultural carbon productivity using the provincial panel data of China from 1994 to 2019, and constructs a mediation effect model to test the effect mechanism of financial support for agriculture on agricultural carbon productivity. The results show that: (1) From 1994 to 2019, China’s agricultural carbon productivity presented an increasing trend, with an average annual growth rate of 2.40%, The improvement of agricultural carbon productivity was mainly attributable to technological progress. (2) Financial support for agriculture has a significant direct promoting effect on the growth of agricultural carbon productivity. It also plays a vital role in promoting the increase of agricultural output and inhibiting the generation of carbon emissions, that is, it has the functions of “maintaining growth” and “promoting emission reduction”. (3)Financial support to agriculture can also affect agricultural carbon productivity through the partial mediating effects of agricultural planting structure and agricultural mechanization level. The mediating effects of the two channels accounted for 16.58% and 11.07% of the total effect, respectively, and the results remained valid after the endogeneity and robustness tests.Therefore, this paper provides empirical evidence for the role of financial support for agriculture in both “maintaining growth” and “promoting emission reduction”, and puts forward some policy suggestions based on empirical results.