<p>Understanding and controlling the distribution of slag film, lubrication status, and friction stress are key to improving slab surface quality and ensuring smooth continuous casting operation. In this paper, a friction/lubrication model coupling the temperature field of the slab and mold with the slag film distribution is established to systematically investigate the evolution of lubrication status within the mold during continuous casting and its effect on friction behavior. This continuous casting process produces sub-peritectic steel and employs a CaO–Al₂O₃-based mold flux. Under the process parameters considered, the total friction force calculated by the model is 12.74 kN, which agrees well with the measured value of 12.85 kN. The lubrication state of the mold flux changes significantly along the casting direction: within 300 mm below the meniscus, the lubrication state is predominantly liquid; between 300 mm and 500 mm, mixed lubrication dominates; and beyond 500 mm, solid lubrication prevails. When the casting temperature increases from 1801 K to 1820 K, the liquid lubrication region is significantly extended; both the liquid and mixed lubrication regions shift toward the mold exit, while the solid lubrication region changes only slightly. The friction characteristics corresponding to different lubrication states are investigated. The friction stress ranges under each state are 400 to 3000, 3000 to 6000, and 6000 to 10000 Pa, respectively. Friction under solid lubrication and mixed lubrication are the main contributors to the total friction force, accounting for 49.7 and 40.0 pct, respectively. The friction force on one wide face is approximately 5.7 kN, and that on one narrow face is about 0.67 kN, with the wide-face friction force being about 8 to 9 times that of the narrow face. This study provides a reference for understanding and coordinating the lubrication and friction behavior within the continuous casting mold.</p>