In order to monitor and diagnose the data quality problem due to communication failure, misinformation from intelligent electric device and data transmission delay of EMS, a kind of EMS data quality control and online monitoring method based on multiple data source calibration is proposed. An integrated information integration platform is designed, and traffic sniffer and decoding methods are adopted to obtain data from multiple source, the alarm and diagnosis procedures for different types of measurements are implemented for data quality monitoring and control. All those applications are integrated into the distributed system architecture, and compared to traditional concentrated system architecture, system efficiency is improved. Application shows that the system not only provides the techniques for automatically checking for data quality control and fault diagnosis, but also supplies a powerful platform for EMS maintenance.