The systematical error of the multi-beam continuum scanning of laser satellite communication mainly arises from the time information feedback and detection part. By analyzing the formula for computing the distance between the target location and the scanning centre, the variation trend of the detection probabilities on different scanning locations with the trend of MSE and the step length is drawn. A conclusion is found that arranging the area of the largest probability of the target satellite appearing on the later position of the scanning tracks can reduce errors happening. The digital simulation of identification probability in a scanning cycle shows that when the system time detection precision reaches 4×10-3s, the error probability will be less than 1%.