As the number of impact loads increases, there is an urgent need to develop a valid method to analyze the power quality problems caused by these multiple impact loads. Taking the Chongqing electric power system as an example, the paper presents an evaluation method for the power quality problem when multiple impact loads are connected into the system, and proposes a comprehensive treatment scheme. A new impact load model is constructed based on the fitting measured data, while the regional equivalent grid is established based on the Ward equivalent and multi-potential equivalent in Thevenin Theorem, then the combined effects on the power quality of Chongqing Grid are studied when multiple impact load models access the equivalent grid. For the case of excessive power quality, several control measures are analyzed, such as increasing access voltage level, installing filter or SVC, and treatment schemes are proposed based on the measured power quality data of impact loads in Chongqing Grid. The validity and accuracy of analysis results are verified by building simulation model in PSCAD, and theoretical reference for the comprehensive treatment when impact loads access Chongqing Grid is provided.