Abstract: The impeller is the core component of the centrifugal compressor, and the high-speed operation of the centrifugal compressor impeller puts forward high requirements for the welding quality of the impeller, and its manufacturing quality and reliability are crucial to the safe operation of the unit. Compared with other welding technology processes, narrow channel impeller welding technology requires a higher level of professional welding technology, and the quality of the arc ignition effect will directly affect whether the subsequent welding process can proceed smoothly. Conventional arc ignition operation methods include direct strike method and scratch method, but they will cause difficulty in ignition due to the narrow impeller channel, which is easy to pollute the weld and lead to defects, which directly affects the welding quality. This paper introduces a new arc ignition method of impeller welding for centrifugal compressor narrow flow channel impeller welding. By testing the arc ignition outside the workpiece, the moment the end of the electrode melts into a droplet and the end of the electrode is in a state of scorching red, the electrode is quickly extended to the weld or the arc closing point of the previous welding for thermal arc ignition at high temperature, so as to achieve rapid arc ignition and ensure the accuracy of the arc ignition position.Practice shows that this method can effectively improve the success rate and welding quality of arc ignition.