There are provided a power supply system for a diesel multiple-unit train, a diesel multiple-unit train including the power supply system, and a traction control method for a diesel multiple-unit train. The power supply system includes: a diesel power pack, a traction inverter connected to a traction motor, and an auxiliary inverter connected to a train load. The power supply system further includes a direct current chopper and a supercapacitor. A high-voltage side of the direct current chopper is connected to the diesel power pack, and a low-voltage side of the direct current chopper is connected to the supercapacitor. The supercapacitor is connected to the traction inverter and the train load.