Abstract: In China, cementing for deep and ultra-deep oil and gas wells faces challenges, e.g. high temperature and pressure, complex formation media, and complex operation conditions, etc. The long-term seal integrity of cement sheath cannot be guaranteed, and conventional cementing technologies and equipment fail to meet the needs. Therefore, new cementing theories and technologies to ensure wellbore integrity are desperately needed. In recent years, Sinopec has improved the theory system of seal integrity of cement sheath for cementing, established seal failure control methodologies of cement sheath under complex operation conditions, and developed high-performance cement slurry with the advantage of anti-channeling, anti-corrosion, anti-leakage, and anti-damage through scientific research. In addition, liner hangers for cementing, multi-stage cement injectors, and associated accessories suitable for deep complex working conditions have been designed, new methods for optimizing cementing design have been established, and new cementing technologies for deep complex oil and gas reservoirs have come into being. In the future, it is suggested to further improve the technical system of characteristic cement slurries, develop green and intelligent environment-friendly materials, strengthen the informatization and intelligence of cementing technology, continuously promote basic theoretical research, and enhance the cementing quality of deep and ultra-deep complex oil and gas wells.