A water valve includes a valve body, a stationary sleeve, and a movable sleeve. The stationary sleeve is received in the valve body, and the movable sleeve is slidably disposed in the stationary sleeve. A partition plate is formed in the movable sleeve to partition the movable sleeve into a cold water cavity and a hot water cavity at two ends respectively. An external wall of the movable sleeve is formed with an annular groove positionally corresponding to the partition plate. When the partition plate is pushed under different pressure of cold water and hot water, the movable sleeve is moved to regulate flow ratio of cold water and hot water. Besides, water is received in the annular groove and the gap between the stationary sleeve and the movable sleeve for cushion and lubrication. Thus, the movable sleeve is easier to move for regulation.