The invention discloses a three-phase nine-switch dual-synchronous motor time-sharing control inverter and a control method thereof. A direct torque method is used to obtain a flux linkage, a torque and a flux linkage angle of a dual-permanent-magnet synchronous motor, switching state vector division sectors of two three-phase permanent magnet synchronous motors are obtained, four directions of torque increase, torque reduction, flux linkage increase and flux linkage decrease can be divided according to sector positions and according to motor rotors of different times, thus bridge arm switch on and off states in different directions can be obtained, the voltage vector tables of the three-phase permanent magnet synchronous motors are obtained by direct torque control, the switching states of the bridge arms are selected through a weight function to control the two three-phase permanent magnet synchronous motors, selection switches can independently control the input of PWM signals of different odd and even times into the inverter, and the time-sharing operation of the two three-phase permanent magnet synchronous motors is achieved. According to the method, the control is simple andclear.