Alternating-current zero-crossing starting circuit

The utility model relates to the field of integrated circuits, and particularly discloses an alternating current zero-crossing starting circuit which comprises a main circuit, the main circuit comprises a single-chip microcomputer, an optocoupler relay and a first bidirectional silicon controlled rectifier, and a sampling pin of the single-chip microcomputer is electrically connected with an input end of the main circuit. An output pin and a power supply pin of the single-chip microcomputer are electrically connected with the two ends of the light receiving end of the optocoupler relay respectively, the optocoupler relay is electrically connected with the first bidirectional silicon controlled rectifier, and a zero-cross detection circuit and a second bidirectional silicon controlled rectifier electrically connected with the zero-cross detection circuit are arranged in the optocoupler relay. According to the utility model, by controlling the successive conduction of the optocoupler relay and the second bidire