The invention relates to a one-way valve which comprises a valve base, a valve deck and a non-return piece. One end of the valve base is provided with internal threads. The valve deck is provided with external threads matched with the internal threads of the valve base. The valve deck is connected with the valve base in a threaded mode. The non-return piece is composed of a metal piece and a rubber piece. The metal piece and the rubber piece are closely bonded together. The outer edge of the rubber piece is provided with a semi-circular protrusion. A round hole is formed in the semi-circular protrusion. A protrusion is arranged on the inner wall of the valve base and connected with the round hole in the semi-circular protrusion on the rubber piece. The rubber piece of the non-return piece is attached to the inner wall of the valve base. The one-way valve is simple in structure, convenient to install, high in practicality, reliable in work and low in manufacturing cost, and improves the non-return sensitivity to different pressure pipelines by replacing the non-return pieces of different thicknesses.