Abstract: For the forward looking infra-red (FLIR) image of complex ground fixed target without available base image,it was difficult to recognize the target due to the serious background clutter and small intensity differences of gray scale between target and background.A target recognition algorithm based on shape template matching was proposed.First,hierarchical multiple threshold algorithm based on constructing Gaussian multi-scale space was designed to test region of interest;Second,to extract shape feature and separate the target and background,fuzzy set theory was introduced;Finally,the modified Hausdorff distance algorithm was used for the precise matching,determining target.Experimental results show that comparing to modified Hausdorff distance algorithm,the matching probability of the proposed algorithm increases nearly 20%,taking time is shortened by 2/3,and comparing to Nprod algorithm,the matching probability increases nearly 30%,taking time is shortened by 1/2,under the pepper noise of 0.3 density,the matching probability is still able to reach 70% more.For recognising FLIR target on complex ground,this method has better performance on matching probability,computing speed and recognition precision.