Abstract: After having been used four years in the curve sector R=600 m,some PD3 hot-rolled rails had fatigue damage of desquamation. The damage cause was analyzed by means of chemical composition analysis,mctallographic examination and hardness testing and so on. The result showed that the contact stress of rail and wheel being too excessive,the superficial metal of rail contact surface generated plastic deformation and forms fatigue crack,when the wearing speed rate was less than the fatigue crack expansion rate,the desquamation occured. And the measures were put forward.