For laser communication acquisition, tracking and pointing system on the spot position detection accuracy demand, based on complementary metal oxide semiconductor detector, light spot position detection accuracy evaluation method, and using this method to quantify the commonly used filtering algorithm on the spot position detection accuracy effect are proposed. High precision displacement platform is used to test camera, random error and systematic error, then the median filtering, mean filtering, high pass filtering, morphology filtering processing of spot images are applied, and the filtered centroid positions are calculated. The light spot position detection accuracy before and after filtering is compared, and the influence of filtering algorithms on detecting position is evaluated. Experiments show that the accuracy of the spot detection can be reduced and the method of avoiding the deterioration of accuracy of the problems mentioned above is proposed according to the experimental results.