A power supply device comprises a shell; the shell is internally provided with a power supply function module; the power module function module is used for converting an external alternating current to different direct currents; the power supply function module also includes a battery charging and discharging control unit; the shell is also provided with a containing groove; the containing groove is selectively provided with a battery or at least one fan; when the containing groove is provided with the battery, the battery is electrically connected to the battery charging and discharging control unit, so that the power supply function module can charge the battery; the battery also supplies power to non-volatile memory through a connecting wire; and when the containing groove is provided with at least one fan, the at least one fan is electrically connected to the power supply function module, so that the power supply function module supplies power to the fan. One rechargeable battery is arranged in the containing groove as an independent power supply for supplying power to several devices, so as to reduce the power supply pressure in supplying power. At the same time, the containing groove can also be provided with the at least one fan, which is used for the heat dissipation of the power supply device or the heat dissipation of the server with the auxiliary power supply device.