Abstract: In response to major strategic needs such as national resource and energy security, and to develop the capability to tap into deep-seated resources, ensure safety, and expand spatial reach, exploration technologies are gradually extending into the deep-to-ultra-deep domains. The high-temperature, high-pressure environments in which rocks are subjected significantly alter their microstructures and morphological characteristics, resulting in complex macroscopic and microscopic mechanical responses that pose severe challenges to engineering safety and resource development. This paper systematically reviews the mechanisms of rock microstructural evolution under high-temperature and high-pressure conditions, advanced experimental observation techniques, multi-scale mechanical modeling methods, and active performance control strategies. Existing research indicates that the coupled effects of temperature and pressure induce mineral phase transformations, drive the evolution of microcrack networks, and reorganize internal stress chain structures; these microscopic changes are the core mechanisms governing rock strength, deformation, and permeability properties. By integrating multidimensional characterization techniques such as scanning electron microscopy (SEM), nanoindentation, micro-CT, and Raman spectroscopy, it is possible to achieve a detailed analysis of mineral composition, microcrack systems, and three-dimensional structures. Building upon this, a quantitative predictive bridge linking microstructure to macroscopic properties has been established using homogenization theory, thermo-mechanical coupling models, and multiscale simulation frameworks. Furthermore, through active strategies such as heat treatment, chemical regulation, and intelligent monitoring based on microstructural information, it is possible to achieve the active design and performance optimization of rock microcrack networks. These insights provide new scientific approaches and technical support for the safe and efficient implementation of major national projects, including scientific drilling, deep resource development, and high-level radioactive waste disposal. In the future, overcoming the technical bottlenecks in deep in-situ dynamic observation and developing intelligent prediction models that integrate physical mechanisms with artificial algorithms will be key to advancing deep rock mechanics toward greater precision and intelligence.