This paper proposes a new monitoring system of power quality, which is combined with the technology of wireless data transmission of SM5X and intelligent instrument. Hardware configuration and software design of the system are also described in this paper. Based on the monitoring system, remote monitoring of power quality parameters, condition diagnosis and alarm can be achieved. This system has been successfully used in copper smelting industry, which proved its stability and excellent scalability. It provides a new idea which improves the cost-effective of remote multi-point monitoring system of power quality. In addition, it also provides a platform to verify the validity of the reactive power compensation device.