Abstract: In order to characterize the effect of hydrogen pressure on crack propagation accurately, the characterization method was analyzed using the fracture mechanics theory, then several finite element (FE) methods were used for calculating the hydrogen pressure effect. According to the loading direction of hydrogen pressure, the mode I crack was chosen as an example. Based on the fracture mechanics reasoning, the theoretical formulas for characterizing hydrogen pressure using stress intensity factors (SIF) under the linear elastic model and the elastoplastic model were obtained. The results of FE calculation showed the J integral method is not suitable for the characterization of hydrogen pressure effect on the crack growth. However, SIF had the considerable rationality and accuracy for characterization. In addition, the displacement method is more suitable than the stress method for calculating the SIF of hydrogen pressure.