Abstract: The economic and ecological functions of ecological farming and breeding techniques have received considerable attention, however, their social functions have been ignored. To explore the social function of ecological farming and breeding technique, this study analyzed the impact of the adoption behavior of integrated rice-crayfish farming techniques on social capital using a treatment effect model based on survey data of 1039 rice-crayfish farmers in the Jianghan Plain, Hubei Province. The results were as follows: 1) The social function of the integrated rice-crayfish farming technique was extremely prominent. In other words, the adoption of the integrated rice-crayfish farming technique significantly boosted the farmers’ social capital. After farmers adopted this technique, the total level of social capital increased by 0.047 units, of which the scale of social networks expanded by 114.266 units, while the status of social networks decreased by 3.595 units. 2) From the mechanism perspective, the adoption of integrated rice-crayfish farming technique boosted farmers’ social capital by promoting their cooperative participation and Internet use. 3) From the heterogeneity analysis, there was income and age heterogeneity in the impact of integrated rice-crayfish farming technique adoption behavior on social capital; the adoption behavior of integrated rice-crayfish farming techniques had a more pronounced effect on the social capital of high-income farmers and farmers under 60 years old. Therefore, it is necessary to understand and evaluate the social functions of integrated rice-crayfish farming technique in order to promote social capital accumulation among farmers.