Abstract: An emergency lighting device with an auto-dimming detection function and used in an inverter system is provided. After receiving sensing signals from a sensor, a control unit of an emergency lighting device outputs signals for control of a dimmer to carry out dimming of a light source and control output power. No matter how many light emitting diodes are mounted in a light emitting diode module of the light source, a battery is further controlled to maintain a fixed output current by control of light brightness of the light source. Thereby not only luminous flux of the light source can be calculated accurately, use and arrangement of the emergency lighting device are easier. Installation cost is significantly reduced and manufacturers can label service time of the device accurately. The emergency lighting device is safer and more convenient to use.