The invention provides an electric power operation monitoring data quality assessment system and method. The system includes a data set extraction module, an abnormity discrimination module, and a data quality assessment module that independently execute scripts codes. The method includes that a needed data set is extracted from an electric power operation monitoring data center; for the target data set, the abnormal electric power data is discriminated by means of data quality assessment indexes and constraint rules, the detected data quality problem is processed, an evaluation method is determined, and the calculation result is stored; and the result information of the data quality assessment indexes is acquired and the visualized operation is selected. The system and method prevent the problem in the data quality assessment process in the prior art, greatly improve the whole data quality assessment efficiency, and can visually perform quantification assessment and result feedback, and thus providing a systematic and comprehensive data quality assessment standard, guaranteeing the accuracy, timeliness, effectiveness, and reliability of data, enhancing the improvement of electric power operation monitoring data quality and further improving the running stability of an electric power system.