The valve with an improved junk ring structure is composed of a main body, a valve disk, a washer and a junk ring. The main body has on one side thereof a stepped surface of which the outermost end has a screw thread portion on the inner wall thereof, the main body has on an inner wall thereof a protrusion. An upper and a lower pivotally connecting block are provided on the valve disk, and are movably connected by an axle provided on the main body. The junk ring has on the outer wall of the periphery thereof a screw thread portion mating with the screw thread portion of the main body. The washer is placed between the main body and the junk ring. By the arrangement of two screw threads (or multiple screw threads) with an identical screwing direction provided respectively on both the screw thread portions of the main body and of the junk ring, the entire valve can be assembled firmer and more convenient, the threads can be formed on a lathe simultaneously to reduce the number of times and the cost of production.