Influenced by many factors, the near-infrared star images have a low SNR. And the background is always non-uniform, it brings great difficulties in the process of picking up near-infrared star target. According to theoretical calculation, near-infrared star images taken in actual daytime have a very low SNR, star targets can not be picked up by common filtering method. Morphology algorithm is excellent to deal with star images. Firstly, the size of targets and noise are analyzed, the structure elements with bigger size are chosen. Based on assembled opening operation and top-hat transformation, the background is picked up and the images which only have targets and noise are got. Then the sizes of structure elements are changed in order to remove the noise and segment the targets. The experiment shows that star target can be perfectly separated.