Liquid-solid (liquid-liquid, or gas-solid) separator features new-type structure, short liquid flowing course, high separation efficiency and easy operation. It comprises primary separation region, circulation channel and secondary separation region, divided by axial inner and outer cylinders. Central overflow pipe is extended into outer cyliner via flange or head plate and inlet pipe goes through outer cylinder into inner one. Said outer cylinder has a conic cylinder with underflow drain pipe and regulating ring at its lower part.