Abstract: The rice and crayfish co-cropping mode is one of the existing ecological agriculture modes widely adopted by the farmers in paddy fields of China. Therefore, clarification of the agricultural input reduction behavior and its influencing factors in this mode has an important effect on the efficient utilization of farmland resources and agricultural sustainable development. By taking 589 rice and crayfish co-cropping farmers from 3 cities in Jiangsu Province as the samples, the agricultural input (including fertilizers, pesticides, and feed) behavior and its main influencing factors in the rice and crayfish co-cropping mode were analyzed based on the farmers' behavioral selection theory and the structural equation model. The results show that most of farmers tend to reduce the input of fertilizers, pesticides and feed in the rice and crayfish co-cropping mode. The farmers' cognition to rice and crayfish co-cropping mode and the external environment have significant positive effects on the agricultural input reduction behavior, and the influence of the former is greater than that of the latter. In addition, the influence factors, including the farmers' cognition that the rice and crayfish co-cropping mode enables the agricultural input reduction, and excessive agricultural input will lead to environmental pollution, the guidance given by the agricultural technology department, agricultural insurance, agricultural subsidies and neighborhood effect all could significantly impact the agricultural input reduction behavior. Accordingly, it is proposed that comprehensive capital endowment of farmers might be improved, the agricultural technology department should increase the efforts to give guidance and strengthen the effect, the support policies and rewards and punishment mechanisms should be improved, and the brand of rice and crayfish should be established.