Speed reducer, drive axle and vehicle

The invention relates to a speed reducer, a drive axle and a vehicle, the speed reducer comprises a planetary gear set, the planetary gear set comprises a sun gear, a planetary gear, a planetary carrier and a gear ring, the sun gear is driven by external power to rotate around a first axis, the planetary carrier is fixed on an external structure, and the gear ring rotates around the first axis along with the sun gear through the planetary gear installed on the planetary carrier; the driving bevel gear is mounted on the outer surface of the gear ring so as to revolve around a first axis, the driving bevel gear can also rotate around a second axis relative to the gear ring, and the second axis is perpendicular to the first axis; the driven bevel gear can rotate around the first axis and is meshed with the driving bevel gear. The rotating speed and the torque received by the sun gear are jointly decelerated through the planet gear, the gear ring, the driving bevel gear and the driven bevel gear, and then can be