Abstract: Primary processing of agricultural products is a necessary process of modern agriculture and an important basis for intensive processing of agricultural products.Primary processing of agricultural products carried out by agricultural machinery system is mainly primary processing of field crops.It is still a weak point in development of agricultural machinery in overall and whole development of agricultural machinery with high quality and high efficiency.Development history and present situation of primary processing of agricultural products，key points and characteristics of agricultural machinery system in developing agricultural products primary processing，and develop measures were discussed.It was suggested that agricultural machinery system should be divided into five modes to build small，convenient，economical and safe primary processing points of agricultural products that serve farmers and agricultural production.Agricultural machinery system should combine with resource advantages and adopt five modes to build small，convenient，economical and safe primary processing points of agricultural products that serve farmers and agricultural production.