Abstract: In view of problems that most of existing intelligent design methods of fully mechanized coal mining equipment are not considered complex coupling relationship among design parameters of three machines matching, which leading to poor applicability of the system and isolated design knowledge, a conceptual design method and matching principle of three machines of fully mechanized coal mining equipment based on knowledge reasoning were studied, the hybrid reasoning mechanism including case reasoning, rule reasoning and model reasoning was applied to the conceptual design of three machines matching of fully mechanized coal mining equipment, reasoning model of conceptual design of three machines matching of fully mechanized coal mining equipment based on the knowledge reasoning was established, conceptual design system of three machines matching of fully mechanized coal mining equipment based on knowledge reasoning was developed. The system uses knowledge reasoning method to do case reasoning of input initial parameters for user, and search similar case in the case database, so as to obtain satisfactory design scheme, if there is no similar case in the case database, parameter design of three machines matching was completed by model reasoning, so as to get parameter design scheme. The application example shows that the system has accurate design result and fast reasoning speed, which realizes intelligent design of fully mechanized coal mining equipment and shorten design cycle of products.