The hinge side of the aluminium sliding window can be sealed by adding hidden hinges. The hinge side of the inner hanging window is close to the middle lock. In the previous design, the single lock point middle lock is generally selected for the window, but the lock point is far from the upper rocker arm hinge, which still can not ensure the sealing effect, especially for high-rise buildings. Therefore, in the future design, 500mm single lock point intermediate lock can be selected for fan height less than 1400mm, and two lock point intermediate lock should be selected for fan height greater than 1400mm, which can ensure good sealing effect.