The invention discloses a portable power supply box for an electric vehicle. The portable power supply box comprises a box body for accommodating a battery. The box body is characterized in that an inner cavity for accommodating the battery is formed in the box body, a pull rod roller device is arranged on the back of the box body, and an interface connected to a circuit of the electric vehicle isarranged on the side face of the box body; a wire storage room for placing a charging wire is arranged at the side face II, close to the box body, of the back of the box body, and an inlet hole for the charging wire is formed in the side face II; the pull rod roller device comprises a telescopic roller mechanism which is movably connected to a pull rod operating mechanism. The portable power supply box has the beneficial effects that according to the scheme, the portable power supply box is simple in structure, reasonable in design and convenient to charge, and is particularly suitable for urban young office workers and urban expressage tricycles.