The invention provides a traffic data quality monitoring system. An itemized monitoring module dynamically monitors equipment operating statuses and data quality of electronic polices, intelligent toll gates and vehicle detectors; a risk early warning module realizes early warning and integrated processing of abnormal data; a decision support module analyzes system abnormal data detection conditions and effective data situations according to processing results of the risk early warning module and a data checking module; a parameter configuration module provides parameter detection and early warning conditions for the itemized monitoring module and the risk early warning module. The traffic data quality monitoring system has advantages that abnormal data can be recognized, detected data quality assessment, checking and treatment can be realized, and accordingly false detection and judgment caused by abnormal conditions such as equipment faults and environment interferences are avoided, workload is relieved for workers, and law enforcement data validity and reliability are guaranteed.