As to the human body tracking problem under the weak light environment, human body tracking algorithm of ant colony detection with pigment information is presented. The character of ant colony optimization algorithm was used to detect the monitoring initial frame image object edge, and in the initial frame image to gather on the edge of the ant colony body, pigment information is marked. By using pigments ant colony detected with pheromone ant colony and toward pheromone ant colony gather, the purpose of tracking for human movement at night is achieved. The experimental data analysis and simulation results show that the human tracking algorithms for human movement under the low light environment is effective, and also has certain robustness for an image with noise.