A power positioning method and a power positioning device thereof are disclosed. The method comprises the steps of: controlling a device to be measured to transmit a plurality of positioning signals by a plurality of transmission powers; causing a plurality of known location devices to receive the plurality of positioning signals and recording the plurality of positioning signals and a plurality of corresponding receiving time to a database; finding out the known location device with a large signal intensity among the received plurality of positioning signals; taking out a signal intensity-distance function and a signal intensity-distance standard deviation function from the database; and finding out a device location of the device to be measured according to the signal intensity-distance function and the signal intensity-distance standard deviation function.