Aiming at the problems of weak anti-interference ability and slow response of current flame detectors,a multi-band composite flame detector is designed.The system is composed of three bands infrared and one band ultraviolet,and the corresponding flame detection algorithm can be programmed at the same time.Compared with the traditional flame detector,it has stronger anti-jamming ability.The experiment shows that the device can de-tect the flame quickly and accurately within 15m,distinguish the true and false fire effectively,the false alarm rate is low,the response time is less than 3s,and it has strong practicability.