A method for tracking multiple maneuvering targets with single observer of IRSTS is presented, It is set up by using the information of the bearing measurements and the sum of the infrared radiation power of the targets received by IRSTS and combining the IMM(Interacting Multiple Model) and the JPDA(Joint Probabilistic Data Association) algorithm.The performance of the algorithm is verified by two scenarios of multiple maneuvering targets tracking.The results show that at the beginning of the tracking, both the scenarios can be tracked effectively; when the targets fly at a forming columns, all the targets can be track effectively at the whole trajectory and the accuracy of the tracking is satisfied; when the targets fly crossly, the RMS position error changes large obviously and give a invalid track to the target at the distance at the end of the trajectory, but the near target can be tracked effectively at the whole trajectory.