The invention discloses a serial-parallel hybrid power drive device of a commercial vehicle. Only one clutch is arranged to achieve serial-parallel working condition switching, the speed increase of a generator is achieved through a speed increase planet row, the speed reduction and torque increase of a motor are achieved through a speed reduction planet row, and both the structure and the process are simple, which facilitates the layout of a power system of the commercial vehicle. The drive device specifically comprises an input shaft, the speed increase planet row, the generator, the motor, the clutch, the speed reduction planet row and an output shaft. In the drive device, pure electric drive or serial hybrid power drive is adopted for the start, low speed and medium speed working conditions; under the serial hybrid power working condition, the motor drives the generator to generate power through the speed increase planet row, the generator can work in an economical fuel consumption section at the moment, and redundant electric energy can be stored in a battery pack for pure electric running of the motor; under the high-speed parallel working condition, the clutch is engaged, power of the motor directly drives the vehicle to run, one time of energy conversion is omitted, and the drive efficiency is improved.