With the development of information technology and smart grid, various electronic components and impact loads are widely used in reality. The power quality problem in the power system is becoming increasingly serious, and the power quality problem has become one of the research difficulties at home and abroad. Aiming at this problem, this paper designs and implements a power quality monitoring system based on an intelligent fusion terminal. By constructing a modular intelligent fusion terminal, the power quality in the power grid can be monitored in real-time, and the power quality problems can be discovered and solved in time. The terminal can not only realize all the functions of the original operation monitoring and metering equipment of the distribution network but also meet the application requirements of the terminal in different distribution networks by configuring the expansion module, which improves the flexibility and scalability of the terminal construction. The results show that the system can monitor the operating parameters such as three-phase current, three-phase unbalance, three-phase voltage, and power factor in real time. At the same time, it can also effectively detect abnormal operating conditions, improve the efficiency of operation and maintenance personnel, and enhance the customer’s electricity experience.