according to the characteristics of infrared image segmentation, using the gene structure tree model. First through the growth of the root node to node order accumulation get properties for the structure tree model; then the decision rules for the calculation of the distance tree branch node, the angle between the said branch node, the smaller the angle, the branch node distance is small; the last one the largest likelihood value as the tree from the gene tree, the algorithm flow is given. Simulation results show this algorithm for infrared image segmentation well reserve the target area, there are more concise and smooth edge, quantitative segmentation quality evaluation results and.