A method for managing power usage is perform at a mobile terminal having one or more processors and memory storing programs executed by the one or more processors. The mobile terminal collects its operating environment information while the mobile terminal is in a first operating mode. The mobile terminal compares the collected operating environment information with a plurality of power usage switch conditions, each power usage switch condition having an associated operating mode, to determine whether the collected operating environment information matches one of the plurality of power usage switch conditions. When this happens, the mobile terminal determines its current working status and switches from the first operating mode to the second operating mode when there is no conflict between the mobile terminal's current working status and the second operating mode associated with the matched power usage switch condition.