A controlling apparatus for an electric drive transmission used in a dual-motor electric vehicle, wherein the dual motors comprises first and second motors (1, 2), the electric drive transmission is coupled with the first and second motors (1, 2) in a way that the first motor outputs power with a single gear, and the second motor selectively outputs power with two gears (5, 7) by means of a single synchronizer, and the controlling apparatus is configured to receive information sent from a vehicle controller, to control operations of the first and second motors (1, 2) and the electric drive transmission, and to perform gearshifting operation of the synchronizer by the steps of: the controlling apparatus starts to intervene in torque distribution of the vehicle controller; when the second motor is in a zero torque state, the synchronizer is shifted to a neutral position, and in this stage, the required torque of the second motor keeps to be zero; after the synchronizer is shifted to the neutral position, if the target gear position is the neutral position, the gearshifting procedure is completed, and if the target gear position is not the neutral position, speed control to the second motor is conducted to adjust its speed towards a target speed; once the speed of the second motor has been adjusted to the target speed, the second motor is subjected to zero torque control, the required torque of the second motor being zero; once the second motor comes into a zero torque state, the synchronizer starts to be shifted to the target gear position, and in this stage, the required torque of the second motor keeps to be zero; once the synchronizer is located in the target gear position, the required torque of the second motor changes towards a target value at a proper changing rate; when the real torque of the second motor and is equal to or larger than target torque, the gearshifting procedure is judged as completed; wherein in Step, the required torque of the second motor changes towards zero torque at a proper changing rate, and at the same time, the torque of the first motor changes towards a target value of the required torque of the first motor which is calculated based on a required torque of the whole vehicle at wheel; and wherein when the second motor is in the zero torque state, the first motor keeps its target value of the required torque to support the power requirement of the whole vehicle. the controlling apparatus starts to intervene in torque distribution of the vehicle controller; when the second motor is in a zero torque state, the synchronizer is shifted to a neutral position, and in this stage, the required torque of the second motor keeps to be zero; after the synchronizer is shifted to the neutral position, if the target gear position is the neutral position, the gearshifting procedure is completed, and if the target gear position is not the neutral position, speed control to the second motor is conducted to adjust its speed towards a target speed; once the speed of the second motor has been adjusted to the target speed, the second motor is subjected to zero torque control, the required torque of the second motor being zero; once the second motor comes into a zero torque state, the synchronizer starts to be shifted to the target gear position, and in this stage, the required torque of the second motor keeps to be zero; once the synchronizer is located in the target gear position, the required torque of the second motor changes towards a target value at a proper changing rate; when the real torque of the second motor and is equal to or larger than target torque, the gearshifting procedure is judged as completed;