Taking dam body and steel liner in the gradual change segment of inlet of a hydropower station as the research target, structure analysis is carried out by use of the large finite element software. Temperature variation load and external pressure load equivalent to internal vacuum 0.2MPa pressure are considered. Stress and distribution of the dam, steel liner and the stiffener rings are obtained. The calculation results show that, steel liner structure in the gradual change segment has sufficient rigidity; the stress state of steel liner structure is very complex and the stress concentration in stiffener rings is significant; the stress value in sharp-angled area of stiffener ring structure is also very high. Anchor reinforcement with radial constraints and transverse stiffeners are suggested to add to the steel liner, so as to improve the force bearing conditions of steel liner structure in the gradual change segment of inlet. The obtained results and conclusions can be referenced for the design of steel liner structure in the gradual change segment of inlet.