Abstract: The steady-state temperature field of horizontal core-filling continuous casting (HCFC) for producing copper cladding aluminum rods was simulated by finite element method to investigate the effects of key processing parameters on the positions of solid-liquid interfaces (SLIs) of copper and aluminum. It is found that mandrel tube length and mean withdrawing speed have significant effects on the SLI positions of both copper and aluminum. Aluminum casting temperature (T_Al) (1003–1123 K) and secondary cooling water flux (600–900 L·h⁻¹) have little effect on the SLI of copper but cause the SLI of aluminum to move 2–4 mm. When T_Al is in a range of 1043–1123 K, the liquid aluminum can fill continuously into the pre-solidified copper tube. Based on the numerical simulation, reasonable processing parameters were determined.