The invention provides a child safety protection lock unit for a sliding sash. The child safety protection lock unit comprises an outer window, an inner window, a slide rail, a safety key, a key hole and a protection lock, wherein the outer window is arranged at the outer side of the inner window, the inner window is arranged at the inner side of the outer window, the slide rail is arranged at the lower part of the outer window or the the inner window, the safety is arranged in the key hole in a plug-in manner, and the key hole is arranged at the central position of the front surface of the protection lock. Through arrangement of a protection lock fixing block, a protection lock slide block and a protection lock main body, rusting and corrosion are prevented; antitheft and safety performances are improved; the application scope of the protection lock is broadened and the protection lock is allowed to adapt to a variety of aluminum alloy doors and windows; maintenance cost is further reduced; and service life is prolonged.