Abstract: Concentration distribution expression of hydrogen diffusion process in multilayer polymer shells, that is the relationship among hydrogen concentration diffusion, time and diffusion distance was derived based on the second Fick's law. In each layer, in a certain diffusion time, the relationship between hydrogen concentration and diffusion depth is parabolic for a certain quality gas, which indicates in the direction of penetrant diffusion the polymer systems are swelled and the penetrant diffuses along the direction of polymer swelling. In different diffusion time, the concentration of ration hydrogen was increased with time delay at the same place. Because polymer free volumn was largened owing to polymer systems being swelled, and the hydrogen's diffusion path was increassed and the diff