Non-return valve

The utility model relates to a non-return valve which can be used with multifunction and can be particularly suitable for use for liquid control in an enclosed condition such as a sterile transfusion system, a blood transfusion device, a transferpettor, etc. in an aseptic condition. The non-return valve is composed of a valve body and a floater piston. Both ends of the valve body can be connected with the cavity of a pipeline. One end in the cavity is fixed with a funnel type piston cover provided with the float piston. The end face of the piston cover is fixed with the end cover of a liquid outlet hole. One end of the float piston is provided with a guide rod. When the piston cover is fixed at the upper end of the cavity, and the valve body can be used as the pipette. When the piston cover is fixed at the lower end of the cavity, the upper end of the cavity is provided with a burette, and the valve body can be used as the transfusion system. The non-return valve of the utility model can effectively avoid pollution and safety accident, and can reduce the operating performance of medical staff.