Due to the particularity structure of the elevator shaft downstream the arch dam, the variation law of the stress along the height is different from that of the general elevator shaft. At present, most studies simplified the internal structure of the elevator shaft downstream the arch dam. This study used the ANSYS finite element software to analyze the variation of the internal structure of the elevator shaft without increasing the internal structure and increasing the internal structure under normal and seismic conditions. The results showed that: when the structure of the elevator shaft is under normal working conditions and seismic conditions, the internal structure of the elevator shaft is mainly compressive stress, and the tensile stress at the joint with the dam is large, and the tensile stress value gradually decreases along the height of the elevator shaft. When the elevator shaft is simulated to increase the internal structure, the compressive stress of the elevator shaft increased in the internal structure of the dam, and the tensile stress value at the joint with the dam reduced. This study provides reference for the design of the elevator shaft downstream the arch dam.