The Bantam-Fan 1500 gas shielded welding machine is the Fronius brand from Austrian and sold by Yantai Pentium company,which is used in national vocational colleges auto body repair（sheet metal） skills competition. But some functional faults occur in use that can not be repaired in China,which brings great inconvenience to the competition. Through research and practice in the process of use,the structure and working principle of this machine are mastered,and the fault phenomena are sorted,including no reaction when pulling gun trigger,severe sputtering and weld porosity,no arc but wire feed motor work,arc without pulling gun trigger.The main causes for the faults are analyzed,and the corresponding maintenance and use precautions are summarized.