Abstract: A novel temperature-preserved core chamber designed for depths exceeding 5000 m has been developed to enhance the scientific understanding of deep oil and gas reservoirs. This temperature-preserved core chamber employs an innovative vacuum layer for temperature preservation and is compatible with a temperature-pressure preserved coring system. The design principles and key parameters of the temperature-preserved core chamber were determined through static analysis. Numerical simulations assessed the mechanical properties of 70, 85, and 100 MPa core chambers under conditions of 120–150 °C. The results demonstrate that the temperature-preserved core chambers withstand the applied stresses without plastic deformation, and the vacuum layer maintains its integrity under these conditions. A 70 MPa class core chamber prototype was manufactured, and system integration tests were performed on a self-developed in-situ coring platform. The system demonstrated stable operation at 70 MPa for 120 min, with pressure fluctuations within 5%. Additionally, the integrated system operated without interference, enabling the successful extraction of cores with a 50 mm diameter. These findings provide valuable theoretical guidance and design recommendations for advancing oil and gas in-situ temperature-pressure preserved coring technologies in high-temperature and high-pressure environments.