The utility model provides a three-phase imbalance monitoring system suitable for a low-voltage power distribution cabinet. The system comprises a digital signal processor DSP, an A/D conversion module, a GPRS wireless communication module, a three-phase voltage signal conditioning circuit, a three-phase current signal conditioning circuit, and a neutral current signal conditioning circuit. The three-phase voltage, three-phase current, and neutral current in the power distribution cabinet are input to the monitoring system through the signal conditioning circuits, through a mixed-radix FFT and a symmetrical component method, three-phase voltage unbalance degree, three-phase current unbalance degree, three-phase voltage fundamental wave amplitude, three-phase current fundamental wave amplitude, and neutral current effective value and other electrical quantities are obtained. The monitoring system sends results obtained by calculation to a data center through GPRS. The detection software of the data center is responsible for receiving, analyzing, and managing the data. Through the system, a power supply company can accurately know three-phase unbalance conditions of each load point in time. Aimed at a solution of manual phase-changing, cost can be effectively reduced, and burden of work personnel is reduced.