1. A method for indoor positioning a target device in an indoor environment, wherein a plurality of wireless ranging devices are deployed in the indoor environment, the method comprising: defining a default positioning weight; scanning the wireless ranging devices for obtaining a plurality of neighboring ranging devices near the target device; calculating a current positioning weight of each of the neighboring ranging devices; comparing the default positioning weight respectively with the current positioning weight of each of the neighboring ranging devices so as to obtain a plurality of reference ranging devices among the neighboring ranging devices; calculating at least a candidate coordinate according to a deploy coordinate of each of the reference ranging devices in the indoor environment; and estimating a positioning coordinate at which the target device is located according to the at least candidate coordinate.