A drum washing machine, comprising: a tub; a drum rotatably provided in the tub; an agitator rotatably provided in the drum and having a water spray hole; a driver in transmission connection with the drum via a main shaft transmitting a torque of the driver to the drum; a planetary gear assembly in transmission connection with the main shaft and the agitator and transmitting a torque of the main shaft to the agitator, wherein the planetary gear assembly is switchable between a first state and a second state; the planetary gear assembly in the first state transmits the torque of the main shaft to the agitator in a same direction, to rotate the agitator and the drum in the same direction; the planetary gear assembly in the second state transmits the torque of the main shaft to the agitator in an opposite direction, to rotate the agitator and the drum in opposite directions; and a water supply device in communication with one of the tub and a water source as well as the agitator respectively, the water supplying device operable to supply water, from either the tub or the water source, to the agitator and to spray the water into the drum through the water spray hole, the drum washing machine characterized in that: when the agitator and the drum are rotated in opposite directions, a rotational speed of the agitator is less than a rotational speed of the drum, and when the agitator and the drum are rotated in the same direction, a rotational speed of the agitator is equal to a rotational speed of the drum. a tub; a drum rotatably provided in the tub; an agitator rotatably provided in the drum and having a water spray hole; a driver in transmission connection with the drum via a main shaft transmitting a torque of the driver to the drum; a planetary gear assembly in transmission connection with the main shaft and the agitator and transmitting a torque of the main shaft to the agitator, wherein the planetary gear assembly is switchable between a first state and a second state; the planetary gear assembly in the first state transmits the torque of the main shaft to the agitator in a same direction, to rotate the agitator and the drum in the same direction; the planetary gear assembly in the second state transmits the torque of the main shaft to the agitator in an opposite direction, to rotate the agitator and the drum in opposite directions; and a water supply device in communication with one of the tub and a water source as well as the agitator respectively, the water supplying device operable to supply water, from either the tub or the water source, to the agitator and to spray the water into the drum through the water spray hole, the drum washing machine characterized in that: when the agitator and the drum are rotated in opposite directions, a rotational speed of the agitator is less than a rotational speed of the drum, and when the agitator and the drum are rotated in the same direction, a rotational speed of the agitator is equal to a rotational speed of the drum. when the agitator and the drum are rotated in opposite directions, a rotational speed of the agitator is less than a rotational speed of the drum, and when the agitator and the drum are rotated in the same direction, a rotational speed of the agitator is equal to a rotational speed of the drum.