Reactive power balance is an important guarantee of power quality in power system. In the 0.4kv low voltage power network, reactive power compensation method to improve power factor and reduce reactive power loss is one of the important means to improve power supply quality, reduce loss and improve equipment utilization. At present, low-voltage reactive power compensation devices mostly use mcu as the main processor, and sample the voltage and current parameters of the power grid through a/d, calculate the reactive power, reactive current or power factor of the power grid in real time, and control the switching of capacitor banks according to the corresponding control strategy to achieve reactive power compensation of the power grid. Due to the low a/d sampling accuracy, large amount of computation, high requirements on cpu computing performance, complex and difficult hardware and software design, low reactive power compensation accuracy, and long system response time, such controllers can only be used in situations where reactive power compensation dynamic response speed is not required. In view of this, a new dynamic reactive power compensation controller based on energy metering chip +mcu is proposed in this paper.