Abstract: In order to address extremely collapse of internally thinned cylindrical shell due to corrosion, experimental and numerical researches on bearing capacity of internally thinned cylindrical shells repaired with fiber composites were carried out. The pristine cylindrical shells and repaired cylindrical shells with different thinning were manufactured and hydrostatic testing was performed. Meanwhile, the nonlinear numerical analysis method was applied to investigate the buckling behaviors of two kinds of cylindrical shells. The effect of repair parameters on bearing capacity of repaired cylindrical shell was explored. The results show that the bearing capacities of repaired cylindrical shells could restore bearing capacity of pristine cylinders and even better. Among repaired condition, the repair thickness significantly improves the bearing capacity of repaired cylinders. However, the repair parameters reach a certain threshold value, the bearing capacities of repaired cylinders remain stabilization. These research findings play an important role in guiding and advancing the application of composite materials in repairing underwater equipment.