Abstract: Cracks are usually generated when a pressure vessel is being manufactured or in the states of fatigue and complex stress, and the existence of these cracks impacts the safe operation of these vessels. In this paper, the influence of the interaction between the axial double inner and outer cracks in the inner and outer walls of the pressure vessel on the stress intensity factor were studied deeply. Firstly, the cylindrical pressure vessel model with axial cracks in the inner and outer walls was established by finite element software FRANC 3D and ANSYS. Then, the influence of the interaction between the inner and outer cracks with different depth-to-length ratios under static and dynamic conditions on the stress intensity factors was analyzed. Finally, the variation curve of the nominal stress intensity factor for different crack depth-to-length ratios was obtained by means of fitting. It is indicated that the interaction between cracks promotes the propagation of the cracks with low depth-to-length ratio, but inhibits that of initial cracks with high depth-to-length ratio. The research results can be used as the reference for studying the propagation mechanisms under the interaction of multiple cracks with different depth-to-length ratios and evaluating multi-crack fracture failure.