Abstract: Residual voltage detection serves as a key technology for feeder terminal units to realize distribution network fault identification and closing interlock. To solve the defects of traditional hardware residual voltage detection circuits, such as fixed thresholds, operation delay and residual voltage missing detection, this paper designs a novel intelligent residual voltage detection circuit. Taking an ultra-low-power single-chip microcomputer as the main control core and equipped with a lithium battery, the circuit can operate independently after power failure. It adopts signal conditioning and hysteresis comparison circuits to improve detection accuracy, and realizes residual voltage identification, direction judgment and state storage through the sleep-wake mechanism. The terminal can complete fault reporting and logic reset after power recovery. Experimental results show that the circuit features accurate judgment and stable operation, and its performance meets and exceeds the relevant technical standards of State Grid.