1. A positioning control method, suitable for an electronic device mounted on a moving vehicle, the electronic device comprising an image-capturing module and a satellite-based positioning module, the positioning control method comprising steps of: capturing a first image; extracting an icon object from the first image; capturing a second image; identifying the corresponding icon object in the second image; calculating a separation distance between the electronic device and the icon object according to a variance of the icon object between the first and the second images and a displacement distance of the moving vehicle; searching a point-of-interest (POI) site corresponding to the icon object from a point-of-interest database; and calculating or calibrating positioning data of the electronic device according to the separation distance and known coordinates of the point-of-interest site; wherein the step of searching the point-of-interest site further comprises: obtaining first positioning coordinates of the electronic device by the satellite-based positioning module; and searching the point-of-interest database according to the icon object within a neighborhood area of the first positioning coordinates, so as to obtain the point-of-interest site; wherein the step of calculating or calibrating the positioning data of the electronic device further comprises: calculating second positioning coordinates of the electronic device according to the separation distance and the known coordinates of the point-of-interest site; and when the first positioning coordinates and the second positioning coordinates are mismatched, calibrating the positioning data of the electronic device according to the first positioning coordinates obtained from the satellite-based positioning module and the second positioning coordinates; wherein, when the first positioning coordinates and the second positioning coordinates are mismatched, the positioning control method further comprises: calculating site coordinates of the icon object according to the separation distance and the first positioning coordinates; reporting the site coordinates after calculation to the point-of-interest database; and updating the known coordinates stored in the point-of-interest database according to the known coordinates of the point-of-interest site and the site coordinates after calculation.