The invention relates to an electric vehicle mobile power supply. The electric vehicle mobile power supply comprises a charging assembly, a storage battery assembly, a main control assembly and an output assembly, wherein the charging assembly is used for converting an external power supply voltage and charging the storage battery assembly; the storage battery assembly is used for storing the electric energy of the external power supply voltage, and charging the electric vehicle; the main control assembly is used for regulating and monitoring charging-discharging parameters of the storage battery assembly; and the output assembly is used for outputting the electric energy of the storage battery assembly to the electric vehicle, and charging the electric vehicle. By adoption of the electric vehicle mobile power supply, the electric vehicle can be charged at any time anywhere, so that the shortcoming that a fixed charging pile cannot move in a charging process is overcome; particularly, the electric vehicle mobile power supply can temporarily charge the electric vehicle which is in low battery to increase endurance mileage of the electric vehicle; and meanwhile, the electric vehicle mobile power supply is safe, reliable, stable, convenient, compact in structure, efficient in operation, and has relatively high promoting significance to the popularization of the electric vehicle.