A method controls a washing machine including a drum rotatably provided in a tub that receives water, at least one nozzle spraying water into the drum, a washing motor rotating the drum, and a circulation pump circulating water within the washing machine. The method includes: controlling a rotation of the drum by operating the washing motor to rotate the drum at a first rotation speed in a first rotation direction, and to maintain a rotation of the drum at the first rotation speed in the first rotation direction so that laundry in the drum maintains contact with an inner circumferential surface of the drum; and controlling a pump speed of the circulation pump by operating a circulation pump motor in the circulation pump to accelerate and decelerate at least once while the washing motor rotates the drum at the first rotation speed in the first rotation direction.