A press-fitting includes a body, a jacket, a seal ring and a plastic check ring. The plastic check ring has an annular convex portion, one end of the jacket has an inward wall for clamping with the inner hook, the body has a seal groove and a serrated groove with fillets on its core portion. The seal ring is disposed in the seal groove with the outer diameter of the seal ring being smaller than or equal to the outer diameter of the core portion. The press-fitting according to the present invention is of simple structure, and is convenient and quick to be assembled, and can be inspected, and is safe on seal coupling.