The invention relates to a washing machine capable of adjusting a water injection direction and a water injection method thereof. The washing machine comprises an outer drum, an inner drum used for washing and dehydration, a water inlet valve, a computer program controller and a water injection box, wherein a water injection adjusting unit is arranged on a water baffle of the water injection box, thus the water injection direction can be changed through automatic control of the computer program controller according to different positions of clothes in the inner drum to ensure that water can be injected to any proper position from the internal surface of the side wall of the inner drum to the center of the inner drum, namely the water is injected to the internal surface of the side wall of the inner drum first and then to the center of the inner drum in a washing process; the water is injected to the center of the inner drum first and then to the side wall of the inner drum in a spraying and rinsing process; and the water is always injected to the internal surface of the side wall of the inner drum in a water storing and rinsing process. By the technical scheme, the clean ratio and rinsing ratio can be improved, and water and time can be saved.