The daily monitoring data of power quality contains rich information. Through the analysis and statistics of these data, the reference basis for decision-making can be obtained. A correct decision comes from the real investigation of the actual situation. Since the power quality monitoring data is the result of long-term monitoring of the actual system, it is more convincing than theoretical speculation. The decisions made based on it are also closer to the actual situation and more feasible. For example, the outgoing line of a substation supplies power to a small steelmaking plant, which causes serious harmonic pollution on the bus of the substation. Through continuous monitoring of the outgoing line and analysis of the monitoring results, a targeted treatment scheme is proposed.