The invention relates to an electric quantity metering method for a vehicle-mounted power battery of an electromobile. The method comprises that 1) a current sampling module samples a discharging current of a vehicle-mounted storage battery, the discharging current is converted into a voltage signal, and the voltage signal is transmitted to a master control device; 2) a vehicle-mounted air conditioner, a video player and an illumination device are connected with a master control device via current sampling modules; 3) a data processing module arranged in the master control device processes the voltage signal received in real time to obtain an electric quantity signal, the voltage signal is converted into an image signal via an image shaping module, the image signal is displayed, and electric quantity consumption of the vehicle-mounted air conditioner, the video player and the illumination device is displayed together; and 4) a distance measuring module arranged in the master control module measures the distance from the present position of the electromobile to a nearest charging station, the data processing module obtains the largest distance for which the electromobile can drive according to present energy consumption of the electromobile and the present electric quanity of the storage battery, and a driver is prompted to adjust electric quantity distribution.