The motor control system for weakly mixed power car consists of an overall control device with motor control unit, an inverter, a low voltage accumulator, a motor and a motor driving hardware part. The motor control unit controls the motor in speed mode, idle mode, generating mode and off mode, and controls the motor to start the engine based on the starting command the overall control device sends out. During starting, the low voltage accumulator powers the triphase winding of the motor through the inverter to realize the set functional requirement, and this can reduce fuel oil consumption in 4-7 %, ensure running comfort and improve environment protection performance.