The invention discloses a vehicle-mounted DC voltage-stabilizing power supply, which comprises a generator and a fixed base, wherein an input shaft of the generator is in transmission connection with an output shaft of an automobile engine, a power output electrode of the generator is connected with an input end of a transformer through a lead wire, an output end of the transformer is connected with an input end of a current rectifier through a lead wire, an output end of the current rectifier is connected with an input end of a filter through a lead wire, an output end of the filter is connected with an input end of a voltage stabilizer through a lead wire, and an output end of the voltage stabilizer is connected with an input wiring post of a power supply socket through a lead wire. The vehicle-mounted DC voltage-stabilizing power supply is provided with an AC-to-DC mechanism composed of the current rectifier, the filter, the transformer and the voltage stabilizer, and is further provided with the generator which is driven by the automobile engine; and an alternating current generated by the generator is converted through the AC-to-DC mechanism and then supplied to external DC electricity-utilization equipment to use.