Abstract: A kind of monitoring system for MOA (Metal-oxide surge Arrester) resistance leakage current was designed. In the design, the chip MSP430 is used as the controller. The system was consisted of the acquisition of leakage current，the count pulse of lightning arrester，wireless receiving / transmitting control，LCD display and so on. The on-line monitoring of MOA can be effectively realized by real-time detecting the resistive leakage current of MOA, and sending it to the RF receive device by wireless.