This application provides a motor control unit, an electric drive system, a powertrain. A first terminal of a power transmission interface of the motor control unit is connected to a first input terminal of an inverter circuit by using a first direct current switch, and a second terminal of the power transmission interface is connected to a first terminal of a switch circuit. The switch circuit includes three switch branches, where first terminals of the three switch branches are connected to the first terminal of the switch circuit, second terminals of the three switch branches are respectively connected to one-phase output terminals of the inverter circuit, and each switch branch includes a controllable switch. The input terminal of the inverter circuit is connected to a power battery pack by using a second direct current switch. Using the motor control unit reduces a volume and hardware costs, and improves applicability.