In view of the features of the non-diffracting laser image, a method to center an image is proposed based on chaotic ant swarm (CAS) algorithm. During the image processing, a servieable area is firstly located, and the maxium luninance for the image is estimated. The difference of the maxium luninance and any pixel luninance of the image is regarded as the objective function.used to search for the whole image using the chaotic ant swarm algorithm. Images were taken at with a camera ( pixel) and image processing was carried out. The experimental results are given to show the efficiency.