A stall alarm for chain breakage protection comprises a power supply module, the power supply module provides a working power supply for a control circuit board element, and the control circuit boardelement comprises a single-chip microcomputer, a crystal oscillator, a serial port driver, an optocoupler and an indicator light. The input end and the output end of the single-chip microcomputer areconnected with the optocoupler. The input end of the single-chip microcomputer receives a speed signal of the rotating speed sensor and a start-stop command of monitored equipment through the optocoupler. The output end of the single-chip microcomputer sends signals to the serial port driver, the indicating lamp and the contact through the optocoupler. The serial port driver is connected with thecommunication interface; the single-chip microcomputer is connected with the crystal oscillator and the dial switch. The anti-interference capability is strong, the operation is stable, and the devicecan be widely applied to most conveying equipment; the intelligent degree is high and the use is simple.