Abstract: In response to the risk of rock instability in deep vertical shafts crossing composite strata with complex geological conditions, based on the large diameter deep vertical shaft of Xianglushan Tunnel in the Yunnan Central Water Diversion Project, a calculation model was established using FLAC3D software.Six monitoring positions were selected to analyze the stability of the shaft surrounding rock during the construction period.The results show that: ① In the absence of structural planes, the deformation, stress, and plastic zone of the surrounding rock were distributed in a circular pattern.The deformation of the surrounding rock gradually decreased from the free face to the deep and was in a compressed state.② As the shaft depth increased, the deformation, stress, and plastic damage depth of Class Ⅳ and Ⅴ surrounding rocks increased significantly.The influence of shaft depth on the deformation and stress growth of Class Ⅳ and Ⅴ surrounding rocks was more significant than that of structural planes.③ For Class Ⅳ and Ⅴ surrounding rocks with large shaft depths, deformation control should be emphasized during construction, and the deeper the well, the earlier the support and reinforcement should be carried out.Meanwhile, the influence of plastic zone depth on the stability of surrounding rock should be considered.The research results can provide a reference for other similar projects.