A spray arm, comprising: a main spray arm; and a plurality of auxiliary spray arms, each auxiliary spray arm being connected to the main spray arm and rotatable relative to the main spray arm, characterized by comprising: a ball assembly arranged at a position where each auxiliary spray arm is connected to and cooperates with the main spray arm, wherein: the ball assembly further comprises a bearing base, and balls of the ball assembly cooperate between an auxiliary spray arm connecting sleeve of the auxiliary spray arm and a main spray arm connecting sleeve of the main spray arm through the bearing base, and wherein the bearing base comprises: an inner sleeve configured to be fitted with one of the auxiliary spray arm connecting sleeve and the main spray arm connecting sleeve; a middle sleeve fitted over the inner sleeve, and provided with a plurality of ball holes, the balls being mounted in the ball holes, and the balls protruding beyond an inner peripheral surface and an outer peripheral surface of the middle sleeve in a radial direction of the middle sleeve; and an outer sleeve fitted over the middle sleeve, and configured to be fitted with the other of the auxiliary spray arm connecting sleeve and the main spray arm connecting sleeve, wherein the main spray arm comprises a main spray arm body and a plurality of main spray arm connecting sleeves, and each auxiliary spray arm is connected to the main spray arm through one main spray arm connecting sleeve, wherein each auxiliary spray arm comprises an auxiliary spray arm body and the auxiliary spray arm connecting sleeve, the auxiliary spray arm connecting sleeve is arranged on a side of the auxiliary spray arm body facing the main spray arm, and the ball assembly is arranged at a position where the auxiliary spray arm connecting sleeve is connected to and cooperates with the main spray arm connecting sleeve, wherein the ball assembly at least comprises a plurality of the balls, and the plurality of balls rotatably cooperate between the auxiliary spray arm connecting sleeve and the main spray arm connecting sleeve. a main spray arm; and a plurality of auxiliary spray arms, each auxiliary spray arm being connected to the main spray arm and rotatable relative to the main spray arm, characterized by comprising: a ball assembly arranged at a position where each auxiliary spray arm is connected to and cooperates with the main spray arm, wherein: the ball assembly further comprises a bearing base, and balls of the ball assembly cooperate between an auxiliary spray arm connecting sleeve of the auxiliary spray arm and a main spray arm connecting sleeve of the main spray arm through the bearing base, and wherein the bearing base comprises: an inner sleeve configured to be fitted with one of the auxiliary spray arm connecting sleeve and the main spray arm connecting sleeve; a middle sleeve fitted over the inner sleeve, and provided with a plurality of ball holes, the balls being mounted in the ball holes, and the balls protruding beyond an inner peripheral surface and an outer peripheral surface of the middle sleeve in a radial direction of the middle sleeve; and an outer sleeve fitted over the middle sleeve, and configured to be fitted with the other of the auxiliary spray arm connecting sleeve and the main spray arm connecting sleeve, wherein the main spray arm comprises a main spray arm body and a plurality of main spray arm connecting sleeves, and each auxiliary spray arm is connected to the main spray arm through one main spray arm connecting sleeve, wherein each auxiliary spray arm comprises an auxiliary spray arm body and the auxiliary spray arm connecting sleeve, the auxiliary spray arm connecting sleeve is arranged on a side of the auxiliary spray arm body facing the main spray arm, and the ball assembly is arranged at a position where the auxiliary spray arm connecting sleeve is connected to and cooperates with the main spray arm connecting sleeve, wherein the ball assembly at least comprises a plurality of the balls, and the plurality of balls rotatably cooperate between the auxiliary spray arm connecting sleeve and the main spray arm connecting sleeve. an inner sleeve configured to be fitted with one of the auxiliary spray arm connecting sleeve and the main spray arm connecting sleeve; a middle sleeve fitted over the inner sleeve, and provided with a plurality of ball holes, the balls being mounted in the ball holes, and the balls protruding beyond an inner peripheral surface and an outer peripheral surface of the middle sleeve in a radial direction of the middle sleeve; and an outer sleeve fitted over the middle sleeve, and configured to be fitted with the other of the auxiliary spray arm connecting sleeve and the main spray arm connecting sleeve, wherein the main spray arm comprises a main spray arm body and a plurality of main spray arm connecting sleeves, and each auxiliary spray arm is connected to the main spray arm through one main spray arm connecting sleeve, wherein each auxiliary spray arm comprises an auxiliary spray arm body and the auxiliary spray arm connecting sleeve, the auxiliary spray arm connecting sleeve is arranged on a side of the auxiliary spray arm body facing the main spray arm, and the ball assembly is arranged at a position where the auxiliary spray arm connecting sleeve is connected to and cooperates with the main spray arm connecting sleeve, wherein the ball assembly at least comprises a plurality of the balls, and the plurality of balls rotatably cooperate between the auxiliary spray arm connecting sleeve and the main spray arm connecting sleeve.