The dairy farming sector is at the base of the dairy industry and is the foundation and lifeline of the industry. The dairy farming industry is an essential subset of China’s animal husbandry. Based on the data on the related costs and benefits of dairy farming in Heilongjiang Province from the "Compilation of National Agricultural Product Cost and Benefit Data", this paper uses the DEA model method to study the production efficiency of four dairy cow farming scales in Heilongjiang Province from 2008 to 2018, and analyzes its comprehensive production technical efficiency and the decomposition items, returns to scale, and the degree of redundancy of input are concluded, the present efficiency ranking of dairy farming in Heilongjiang Province is ordered as mid-scale, large-scale, smallscale, and free-ranging; individual investors have significant redundancies in input of feed and cost. The degree of redundancy in the medium-scale is relatively low, and the redundancy in the large-scale is mainly in terms of costs,and the redundancy of the small-scale aquaculture is only lower than that of the free-range mode. Generally speaking, the dairy farming industry in Heilongjiang Province still needs to be improved and has a lot of room for development. Therefore, it is necessary to propose targeted strategies according to different farming scales. For individual and small-scale farming, the consciousness of scale and efficiency is particularly important. Large-scale breeding needs to pay more attention to management efficiency, so as to reduce the redundancy of breeding investment, fundamentally increase the economic benefits of breeding farms, and promote the development of Heilongjiang Province into a strong animal husbandry province.