1. A method of positioning a plurality of targets, wherein all targets to be positioned move within a spatial area, the method comprises: providing an infrared light source on each of the targets to be positioned; controlling the infrared light source on each of the targets to be positioned to be turned on and off by turns according to a preset sampling frequency; gathering infrared gray scale images of the space where the targets to be positioned are located according to the preset sampling frequency; and positioning one target to be positioned individually in each of the gathered infrared gray scale images.