A power driving system for an electric vehicle, the electric vehicle comprising a first motor, the power driving system comprising: plural configuration-variable series-type battery boxes (110, 120, 130); a first DC bus electrically connected with the plural configuration-variable series-type battery boxes (110, 120, 130) for selectively receiving electric energy from the plural configuration-variable series-type battery boxes (110, 120, 130); a second DC bus electrically connected with the plural configuration-variable series-type battery boxes (110, 120, 130) for selectively receiving electric energy from the plural configuration-variable series-type battery boxes (110, 120, 130); a first drive power transistor module electrically connected between the first DC bus and the first motor; a second drive power transistor module electrically connected between the second DC bus and the first motor, wherein the first motor is driven by the first drive power transistor module and/or the second drive power transistor module; and a first power converter electrically connected between the first DC bus and the second DC bus, wherein after the power driving system is changed from a steady state power mode to a driving voltage switching mode, a driving voltage switching process is performed, wherein if the first DC bus is in a steady state and the second DC bus is in a standby state while the driving voltage switching process is performed, the first power converter uses a voltage of the first DC bus to charge the second DC bus, or if the second DC bus is in the steady state and the first DC bus is in the standby state while the driving voltage switching process is performed, the first power converter uses the voltage of the second DC bus to charge the first DC bus, wherein when the power driving system is in the steady state power mode, the plural configuration-variable series-type battery boxes (110, 120, 130) provide electricity to one of the first DC bus and the second DC bus corresponding to one of the first drive power transistor module and the second drive power transistor module that provides the electric energy to the first motor, and when the power driving system is in the driving voltage switching mode, one of the first drive power transistor module and the second drive power transistor module originally in the steady state power mode decreases the output power and one of the first drive power transistor module and the second drive power transistor module which originally in the standby state gradually increases the output power. plural configuration-variable series-type battery boxes (110, 120, 130); a first DC bus electrically connected with the plural configuration-variable series-type battery boxes (110, 120, 130) for selectively receiving electric energy from the plural configuration-variable series-type battery boxes (110, 120, 130); a second DC bus electrically connected with the plural configuration-variable series-type battery boxes (110, 120, 130) for selectively receiving electric energy from the plural configuration-variable series-type battery boxes (110, 120, 130); a first drive power transistor module electrically connected between the first DC bus and the first motor; a second drive power transistor module electrically connected between the second DC bus and the first motor, wherein the first motor is driven by the first drive power transistor module and/or the second drive power transistor module; and a first power converter electrically connected between the first DC bus and the second DC bus, wherein after the power driving system is changed from a steady state power mode to a driving voltage switching mode, a driving voltage switching process is performed, wherein if the first DC bus is in a steady state and the second DC bus is in a standby state while the driving voltage switching process is performed, the first power converter uses a voltage of the first DC bus to charge the second DC bus, or if the second DC bus is in the steady state and the first DC bus is in the standby state while the driving voltage switching process is performed, the first power converter uses the voltage of the second DC bus to charge the first DC bus, wherein when the power driving system is in the steady state power mode, the plural configuration-variable series-type battery boxes (110, 120, 130) provide electricity to one of the first DC bus and the second DC bus corresponding to one of the first drive power transistor module and the second drive power transistor module that provides the electric energy to the first motor, and when the power driving system is in the driving voltage switching mode, one of the first drive power transistor module and the second drive power transistor module originally in the steady state power mode decreases the output power and one of the first drive power transistor module and the second drive power transistor module which originally in the standby state gradually increases the output power.