The invention discloses an uninterruptedly powered handset and a use method. The uninterruptedly powered handset comprises a main battery, an auxiliary battery and a power supply management and control module which is connected with two power supplies and controls the conducting state of the power supplies. The use method comprises the following steps: (1)connecting a main power supply, and disconnecting an auxiliary power supply; (2) supplying power to the handset by the main power supply; (3)checking whether the voltage of the main power supply is lower than working voltage or not; if so, executing step (4); if not, executing step (2); (4) displaying prompting information, disconnecting the main power supply, and connecting the auxiliary power supply; (5) supplying power to the handset by the auxiliary power supply; (6) checking whether the handset needs charging or not or the main battery needs changing; if so, executing step (2); if not executing step (7); (7) checking whether thevoltage of the auxiliary power supply is lower than latch voltage or not, if so, executing step (8), if not, executing step (6); (8) displaying prompting information; (9) checking whether the handsetneeds charging or the auxiliary battery needs changing; if so, executing step (6); if not, shutting down the handset. The invention can automatically switch power supplies when the handset is in use.