Abstract: This article analyze the case of power quality in automobile manufacturing processing, there are several indexes exceed the limits, which are caused by the manufacture of automobiles. Then we find out that there are mainly four procedures may cause excess of power quality, which are stamping, soldering, coating and final assembly. On this basis, we aimed at the power quality of these four procedures, we summarize lots of problems that had appeared during all these four nodes. We collect several important indicators of power quality during the process, such as voltage sag and voltage swell, harmonic current, three-phase voltage unbalance, etc. Then we put forward a new method called “significant indexes rapid evaluation” to do the estimation about power quality of the automobile industry. By this way, we can allot different weightiness to the indexes according to the different stages of auto production line, and then by weighted calculation, we can directly determine the power quality is qualified or not. Because the entire car production line is highly integrated, any problems in the process will cause the entire production line to be shut down. By using “significant indexes rapid evaluation” method, we can get the result about every procedure of automobile industry. We can also obtain a clear status of economic losses from the evaluation result, then we can give advice to the improvement for the automobile industry production line, so that reduce the risk of the whole factory.