Abstract: With the global energy structure transitioning toward low-carbon development, large-scale storage of hydrogen, a clean and efficient secondary energy source, has become a critical challenge. Geological hydrogen storage involves injecting hydrogen into suitable subsurface formations under high-pressure conditions to achieve seasonal peak shaving, enhance energy security, and support the hydrogen energy supply chain. Owing to its large capacity, low cost, and high safety, it is considered one of the most promising storage technologies. The main types of underground hydrogen storage include salt caverns, depleted oil and gas reservoirs, Saline aquifer, and engineered rock caverns. This study conducts a comparative analysis of hydrogen storage mechanisms under different geological conditions and establishes calculation models for storage capacity evaluation. The research results indicate that salt caverns are suitable for small-scale hydrogen storage, featuring high safety, low leakage rate, high purity, and relatively low cost. Benefiting from the ultra-low permeability and self-healing properties of rock salt, salt cavern storage is currently the most mature and technically reliable option. Depleted oil and gas reservoirs and saline aquifers are suitable for large-scale hydrogen storage, featuring high safety and low cost. however, they face challenges such as higher leakage risks, lower recovery efficiency, and complex hydrogen–formation fluid interactions. Artificial mine cavern hydrogen storage offers flexible site selection, good self-stability, small deformation, and stable storage capacity. but suffers from difficult construction technology, small storage capacity, and high cost. The findings of this research provide a theoretical and technical basis for the scientific site selection and design optimization of underground hydrogen storage facilities.