The detection for mutation point which suddenly appear and vanish has received much attention in IRST application. With the development of multi-wave band IRST system, a sequential infrared target trajectory detection algorithm based on generalized cumulative sum was proposed. The research extended the single band detection into multiple band detection, which improved the detection probability, greatly reduced the average detection delay and signal-to-noise ratio(SNR) under a certain false alarm rate. Results of simulation analysis show that the modified algorithm has excellent detection performance for infrared mutation point target. In case of a certain false alarm rate, the SNR threshold can be decreased to 60% and dual band detection delay can be reduced about a half comparing with the traditional detection method.