Abstract:A fault diagnosis expert system(DMMES) was designed, which aimed at a series of problems of double row and multifunction bagmaking machine, such as, error of photoelectric sensor, the over speed and temperature control failure in running of the machine, and etc. The DMMESs construction structure, the knowledge base, the inference machine and the knowledge of design and validation method were emphatically introduced, and an experimental verification was given at last. Experimental examples results show that the designed fault diagnosis expert system can effectively solve the failure of to double row and multifunction bagmaking machine, and give some suggests. It shows that can achieve the ideal effect.