A visitor grouping method determines whether different visitors belong to an identical group according to a distance between the visitors and an initial position of the visitors in an image sequence, so as to analyze a proportion of number of individual visitors to number of grouped visitors. Furthermore, the visitor grouping method may further determine whether two groups belong to an identical group according to a distance between the groups and an initial position of the groups in the image sequence. Moreover, the visitor grouping method may determine whether a child group exists and then merge the child group with other groups. Accordingly, a specific site may design the display content and manner with respect to the properties of the visitors, so as to enhance service quality and operating efficiency.