The invention relates to a power bi-shunting reduction gear box, comprising a planet differential reducing gear; wherein the planet differential reducing gear is provided with an input terminal and two output terminals, the input terminal is connected to one power output shaft, and power is output by virtue of the two output terminals. The input terminal of a first parallel axis reducing gear is connected to one output terminal of the differential planet reducing gear; and the input terminal of a second parallel axis reducing gear is connected to the other output terminal of the differential planet reducing gear. The input terminal of a first differential planet reducing gear is connected to the output terminal of the first parallel axis reducing gear, the output terminal of a second planet reducing gear is connected to the output terminal of the second parallel axis reducing gear, and the output terminal of the first planet reducing gear and the output terminal of the second planet reducing gear are respectively meshed with a rack by virtue of a climbing gear.