A method for selecting a plurality of base stations to position a mobile device is provided. The method includes selecting a plurality of base station sets from the plurality of base stations, wherein each of the plurality of base station sets corresponds to a distance matrix, utilizing a first artificial neural network (ANN) unit to select a predefined number of the plurality of base station sets from the plurality of base station sets according to a plurality of distance matrixes corresponding to the plurality of base station sets; and utilizing a second ANN unit to position the mobile device according to the predefined number of the plurality of base station sets.