A novel infrared target tracking metho d with tightly coupling particle filer (PF) and mean shift is proposed in order to improve the accuracy and robustness of tracking.Based on the PF,a five-parameter set (2-D central location,width,height,and orientation) is utilized as state vector to describe a random particle sample,and then the adap tive mean shift is introduced as an iterative seeking procedure,in which particles move toward the maximal posterior kernel density e stimation of target state.The weights of particles are updated by the Bhattacharyya coefficient as the mean shift iterative operat ion.Finally,the weighted particles are used to track the infrared target.Experimental results indicate that the number of particles (N=15) needed in the proposed method is much less than that of the classical PF.Compared with the existing methods combining PF an d mean shift,the tracking error of the proposed method is greatly reduced (about 1/3-1/4) at the cost of the tracking time increase by on ly 14%,and the accuracy and robustness are significantly improved.The proposed method can track the infrared target stably and accurately even at complicated background.