Developing countries generally face the problem of sustainable agricultural production during the process of agricultural modernization. Farmland trusteeship is an emerging mode of sustainable agricultural production and has played an important role in China. At present, the Chinese government has taken it as a pilot mode, but its effect also depends on the extensive participation of peasants. Based on the theory of planned behavior (TPB) and structural equation model (SEM) method, the paper analyzed peasants’ participation intention, behavior, drivers, and the influence of policy support on peasants’ participation behavior, using survey data of Jiangsu province and peasants’ participation variables. The results suggest that: (1) The behavioral attitude, subjective norms, and perceived behavioral control variables of peasants’ participation in farmland trusteeship have a significant direct impact on peasants’ willingness to participate, and these three factors indirectly influence peasants’ participation behavior by influencing peasants’ intention; (2) perceptual behavioral control variables such as the size of farmland trusteeship organization had no significant influence on peasants’ participation behaviors; (3) government policy support has a direct and significant impact on peasants’ participation behaviors. These findings not only generate broad direct implications for Chinese policymakers to improve peasants’ participation for sustainable agricultural production, but also provide lessons for other developing countries for agricultural modernization.