Abstract: Deep and ultra-deep layers are important areas for large-scale increasing oil and gas reserves and productions in the future, and reservoir geomechanics is crucial to their exploration and development, which can provide important support for efficient development of deep and ultra-deep oil and gas. Based on the summary of deep and ultra-deep geomechanical characteristics, technological innovation and practical applications, the paper explores future directions and challenges. The results show that: (1) the change of rock mechanical properties under high temperature and high pressure conditions in deep and ultra-deep layers is the basis for disturbing geomechanical properties of reservoirs, and changes in mineral particles, crystal structures, and interactions at the microscopic scale are the fundamental reason. (2) The development of (ultra-) high temperature and high pressure true triaxial rock mechanics instruments, quantitative expression of microscopic rock mechanical properties, and big data intelligent driven prediction technology has provided technical paths and conditions for the development of deep and ultra-deep reservoir geomechanics. (3) In the future, the mechanical properties of rocks under extreme high temperature and high pressure conditions, accurate characterization and four-dimensional dynamic prediction of in-situ stress fields, characterization of deep and ultra-deep reservoir fracture systems and seepage-mechanical synergy mechanisms based on multidisciplinary integration and multi-scale and multi-field coupling simulation should be largely focused.