The traditional methods for power quality monitoring have the disadvantages of large amount of data processing, incomprehensive data collection, and unable to grasp the power quality indicators in real time. In this paper, the implementation of real-time and online monitoring the power quality is discussed, and a new type of power quality monitoring system is designed. The system with three-layer distributed structure integrates the subsystems with different monitoring objectives into a platform, improving extensible ability of the system and capabilities of power quality monitoring in large regional power system. It is shown from actual operation that the system can monitor power quality parameters accurately and reliably in real time, and is of good event handling function for transient power quality, greatly enhancing the capabilities of monitoring power quality by electric utilities.