The utility model discloses a power supply device for guaranteeing?power supply. The device comprises a UPS host machine, a lithium battery cabinet, a charging and discharging cabinet and a super capacitor cabinet. The UPS host machine ensures that when an external main power supply is cut off, the lithium battery cabinet and the super capacitor cabinet are matched mutually for providing power continuously for the user, and ensures that power quality sensitive-type electrical equipment can work normally and continuously. The lithium battery cabinet maintains relatively stable load current output, and mainly provides average load power for the user. The lithium battery cabinet has an advantage that the energy density is high, which can guarantee energy storage capacity of the whole power vehicle. The super capacitor cabinet is connected with the direct current bus of the UPS host machine via a step-down charging circuit and a step-up discharging circuit. The quick charging and large-current discharging capabilities of the super capacitor cabinet guarantee the short-time large-current output capabilities of the power vehicle.