An emergency power source comprises a housing. A battery pack (4) is arranged in the housing for storing electric energy. The input end of the battery pack (4) is connected to a charging circuit (1) for charging the battery pack (4) and the output end of a solar energy panel input circuit (2), the output end of the battery pack (4) is connected to a heavy-current output circuit (7) for outputting a heavy current when an automobile starts, and an external battery intelligent detection system (6) is connected between the battery pack (4) and the heavy-current output circuit (7). The emergency power source is convenient for charging, can output a heavy current for starting an automobile, and can also accurately control heavy-current output.