Aiming at the erosion of CX-2002U carbon composite under the hydrogen plasma of HL-2M divertor, the influence of hydrogen plasma on it is investigated by using the linear plasma device (SCU-PSI) to simulate the operating environment of HL-2M. Under the condition of constant flux, it is found that the erosion of samples by hydrogen plasma is a cycle process through studying the chemical erosion of samples by hydrogen plasma with different irradiation time. In addition, it is found that the impurities in the hydrogen plasma can enhance the erosion of samples as the impurity gases are injected into hydrogen gas.