Abstract: With the accelerated advancement of marine new energy engineering construction in China, a rapid growth in the demand for HVDC/HVAC submarine cables was witnessed. During the manufacturing process of high-voltage submarine cables, by-products generated by the cross-linking reaction were retained inside the insulation layer, which was liable to cause localized charge accumulation and subsequently induce insulation breakdown during voltage withstand tests. The degassing process was not only capable of effectively removing cross-linking by-products and improving the electrical performance of the insulation, but also of eliminating residual stress within the material; therefore, its importance became increasingly prominent. It was demonstrated by research that the degassing effectiveness was closely related to the oven temperature. In this paper, the influence of temperature stability control in the improved cross-linking degassing process on the product quality and operational stability of submarine cables was systematically investigated through theoretical analysis, thermogravimetric analysis, and degassing experiments. The results indicated that the optimized process could effectively enhance the degassing efficiency and shorten the treatment time. The intrinsic coupling mechanism among temperature, degassing efficiency, and insulation performance was revealed, providing a theoretical basis and engineering guidance for the temperature optimization control of the degassing process of high-voltage submarine cables.