Abstract: This paper introduces a developed SMAW expert system for mild and alloyed structural steel.The SMAW has abilities to select covered electrodes, to determine welding conditions,to search data and information relative to electrodes and to present consultations of selected electrodes and specifications of welding technology etc.,so as to be a guide to practical welding production. This system is characterized by its integrated unit,high quality in consultation and efficiency,versatility, as well as convenience in operation.