Abstract: Co-farming technology of rice and crayfish could contribute to good economic, ecological and social effects. whereas farmers’ adoption confronted with multiple constraints because of inadequate sources of effective technology diffusion and high technical risk and economic risk. Based on a field survey dataset of farmers in Hubei Province and Jiangsu Province, this paper analyzes the influence of neighborhood effect and agricultural technology diffusion on farmers’ adoption of co-farming technology of rice and crayfish. After that, we analyzes the complementary and substitution effect of neighbourhood effect and agricultural technology diffusion on farmers’ adoption of co-farming technnology of rice and crayfish. The main findings are as follows: 1）Neighbourhood observation learning and communicating experience are both significantly positive to promote farmers’ adoption of co-farming technnology of rice and crayfish. 2)The diffusion of agricultural technology in agricultural enterprises has a significant positive impact on farmers’ adoption of co-farming technnology of rice and crayfish. 3)About the influence on the adoption of co-farming technnology of rice and crayfish in farmers, there are some substitution effects of Neighbourhood observational learning and agricultural technology diffusion, and so does the social norms; Some substitution and complementary effect of communicating experience and agricultural technology diffusion; Based on the above conclusions, this paper puts forward some policy suggestions to improve the operation efficiency and practical influence of each agricultural technology diffusion agent by combining the complementary and substitution effects of neighborhood effect, so as to improve the normality and efficiency of farmers’ adoption behaviors.