A controlling apparatus and method for an electric drive transmission used in a dual-motor electric vehicle are disclosed, wherein when the second motor 2 is in the zero torque state, the synchronizer is shifted to a neutral position, the second motor the required torque being kept to be zero; after shifted to the neutral position, if the target gear position is the neutral position, gearshifting is completed, an 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 second motor is adjusted to the target speed, the second motor is subjected to zero torque control, the second motor the required torque being zero; once the second motor comes into a zero torque state, the synchronizer 6 is shifted to a target gear position, the required torque of the second motor being kept 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; once the second motor real torque and is equal to or larger than target torque, gearshifting is judged as completed. Loss in wheel driving torque caused by the second motor in the whole gearshifting procedure is compensated by the first motor 1, so that gearshifting without power interruption can be achieved.