A motor controller, a powertrain, and a vehicle are disclosed and relate to the field of new energy vehicles, and may be used in a pure electric vehicle and a hybrid vehicle. The motor controller includes an inverter circuit and a control circuit. The control circuit controls, in response to that an absolute value of a torque requirement indicated by a torque signal is greater than or equal to a preset torque value, the inverter circuit to output a three-phase alternating current. The control circuit controls, in response to that a rotation speed of the motor is less than a first rotation speed value or greater than a second rotation speed value and that the absolute value of the torque requirement indicated by the torque signal is less than the preset torque value, a plurality of switching transistors in the inverter circuit to be cut off.