Cyclic steam stimulation (CSS) is a common method for heavy oil reservoir, but the current research on steam channeling in horizontal wells is limited. This study proposes a novel mathematical model based on steam override to predict steam channeling during the CSS process in horizontal wells, focusing on the quantization of the heated region, steam front edge position, and steam channeling time. The model was validated through a 3D physical simulation experiment. The experimental results were broadly consistent with the theoretical predictions. The study finds that steam channel is an upward-curved wedge shape, making it difficult to mobilize the bottom reservoir. The steam channeling time was predicted to be 10.10 min, with an 11.16% error compared to the experimental value of 8.97 min. Furthermore, the introduction of foam increased the oil steam ratio from 1.52 to 1.92. Reducing appropriately the steam injection rate, increasing well spacing, and decreasing steam temperature, together with periodic foam injection, can delay steam channeling. In conclusion, the model offers practical insights for steam channel prediction, which can improve the effectiveness of steam injection strategies in heavy oil reservoirs.