Abstract: Agricultural mechanization has led to increased energy consumption in agriculture, becoming a widely discussed factor restricting China"s agricultural carbon peak. However, what is often overlooked is that agricultural mechanization also results in the reallocation of agricultural inputs, such as chemicals, and adjustments in crop planting structures, which in turn introduce uncertainties into the changes in China"s agricultural carbon emissions. This paper provides a detailed analysis of the impact of agricultural mechanization on China"s agricultural carbon peak by clarifying these pathways. Based on county-level data across the country, this paper empirically analyzes the impact of agricultural mechanization on agricultural carbon emissions in China using a fixed effects model. Furthermore, a simultaneous equations model is employed to empirically test the pathways of this impact from the perspectives of chemical inputs and rice planting. The research findings indicate that (1) with the increase in the intensity of agricultural mechanization, agricultural carbon emission intensity first increases and then decreases in an inverted U-shape, with the turning point occurring when the intensity of mechanization reaches 87.5 kW/ha, much higher than the current national average level; (2) as the intensity of agricultural mechanization increases, the intensity of agricultural chemical inputs, such as fertilizers and pesticides, follows a similar inverted U-shape pattern, becoming the dominant factor driving the inverted U-shape trend in agricultural carbon emission intensity; (3) as the intensity of agricultural mechanization increases, the proportion of rice planting area initially decreases and then increases in a U-shape, but this is not sufficient to reverse the inverted U-shape trend of agricultural carbon emission intensity. Therefore, in the early stages of agricultural mechanization, agricultural carbon emission intensity will increase, becoming a factor restricting the agricultural carbon peak. However, when agricultural mechanization reaches a certain level, it will contribute to agricultural carbon reduction. This inverted U-shape trend is mainly due to the similar changes in agricultural chemical input intensity. Based on these findings, it is crucial to accelerate the process of agricultural mechanization to promote agricultural carbon reduction, while enhancing environmental management of agricultural chemicals and optimizing agricultural production structures in the early stages of mechanization to drive further carbon reduction in agriculture.