Mechanical Bar Screen is provided with several special-shaped teeth which are assembled on the teeth axis based on certain ordering, forming the sealed teeth chain. The lower part is installed in the water inlet. If the chain wheel rotates directionally with even speed, the whole rake chain will move accordingly. Under such circumstance, the solid sundries attached on the tooth will be separated from liquid and the fluid will low away through the gap. When rake chain arrives at its upper end, each group of rakes will carry on self cleaning by dropping out most of the solid material under gravity and guideline rail, while the rest of the solid will be tidied clean by back running brush.The whole process is carried out continuously and automatically so as to achieve the goal of solid-liquid separation.