A method for reducing the number of the times of switching communication channels and a mobile device are provided. The method includes following steps: determining whether the mobile device is at a stationary state or a semi-stationary state according to a plurality of location information of the mobile device during a predetermined time interval; recognizing an area where the mobile device is located and a communication mode of the mobile device when the mobile device is at the stationary state or the semi-stationary state; establishing a transmission power variation table according to a plurality of transmission powers used by the mobile device at the communication mode; searching for a specific transmission power which is most frequently used from the transmission power variation table; increasing a lowest allowable transmission power of the mobile device to a target transmission power higher than the specific transmission power; and recording the target transmission power.