As socialism with Chinese characteristics enters a new era, China's agricultural and rural development has also made remarkable achievements. However, the shortcomings of modernization are still in the field of agriculture, rural areas and farmers. The report of the 19th National Congress of the Communist Party of China proposes a strategy of rural revitalization. It is pointed out that the organic connection between small farmers and modern agricultural development should be promoted. In the development of modern agriculture, small farmers face the problems of scattered production factors, aging labor force and low labor quality, low industrialization, and low market position. This paper compares the characteristics of farmer cooperatives with other new business entities. Combined with the relevant contents of the Law of the People's Republic of China on Farmers’ Professional Cooperatives newly revised in 2017, this paper analyzes the organizational, service, and intermediary functions of farmers' cooperatives to promote the organic connection between small farmers and modern agriculture development and reveals the role of farmers' cooperatives in China's agricultural development.