The invention discloses a self-detection emergency power supply. The emergency power supply [1] is provided with an outage detection module [2], a warning device [3] and a remote communication module [4]; the outage detection module [2] regularly switches off the emergency power supply, detects battery electric quantity of the emergency power supply and judges whether the emergency power supply can be normally used; the warning device [3] sends warning information in a sound form or an LED (light-emitting diode) lamp light display form when the outage detection module [2] detects the failure of the emergency power supply; the remote communication module [4] sends failure information to an appointed remote number when the outage detection module [2] detects the failure of the emergency power supply. According to the self-detection emergency power supply, the effective working condition of the emergency power supply can be monitored irregularly, and the warning information is sent timely when the emergency power supply fails actually.