The utility model provides a low-voltage fault live display device comprising an external electrical connecting line which is connected on a live body measuring point between a meter and a user air switch. An RC series-connected circuit is connected in the electrical connecting line. An LED light-emitting diode used for displaying the live state is also connected in series on the RC series-connected circuit at least. A protection diode is connected in parallel on the LED light-emitting diode. A color ring resistor convenient for maintenance and detection is selected as a resistor of the RC series-connected circuit, and a thin-film capacitor is selected as a capacitor of the RC series-connected circuit. The low-voltage fault live display device has characteristics of being simple in structure and convenient to use and install, and fault equipment can be detected and the fault type can be judged by a user via observing the lighting condition of a live displayer so that fault detection time can be reduced for the user, and efficiency of first-aid repair work can be enhanced.