Under the background of socialized small-scale farming operation, the complexity of farming households’ willingness and behavior directly affects the diversity of farmland function supply. By summarizing the behavioral characteristics of socialized small-scale farmers and taking farming households’ response to the demand for agricultural land multi-functions as the intermediary factor, this study constructed a conceptual path analysis model, and used the structural equation (SEM) to fit the model to analyze the direct effects of farming household differentiation on the diversification of agricultural land function supply and its indirect effects through the intermediary factor as well, in order to explore the influences and paths. The empirical study of six research areas in Huangpi, Xinzhou, Ezhou, Jiangxia, Tongshan, and Caidian of Hubei Province showed that the differentiation of farmers has both direct and indirect negative effects on the diversification of farmland function supply. The more livelihood capital the farming households possess, the lower the diversity of farmland functions they supply. The direct negative effects of farmer differentiation on the diversification of farmland function supply mainly come from the substitution of some production factors caused by the externalization of agricultural production conditions under the trend of socialized small-scale farmers, such as the weakening of ecological function of agricultural land caused by the loss of high-quality labor force and the substitution between the elements of labor force and chemical fertilizer or pesticide; while the indirect negative effect are mainly from the mismatch of three types of production factors which means the input of the three types of factors has not reached incentive compatibility, thus affecting the output efficiency of agricultural land multi-functions. Therefore, we need to pay attention to the new connection and infiltration of production factors, and make them compatible with material elements. As far as our research areas are concerned, first, it is necessary to broaden the traditional way of agricultural land use, deepen farmers’ cognition of the external production conditions of agricultural land, and alleviate the dependence of farming households on external production conditions by means of social security and finance, so as to attract high-quality agricultural labor force to return; in addition, it is also necessary to improve the transfer of land rights and build an information exchange platform to promote the multi-functional utilization of agricultural land.