Abstract: This study investigates personnel evacuation path planning in underground the coal mine fire scenarios, with a mine in Shanxi Province, as a case study. The height, temperature, visibility and CO concentration of the smoke layer under two kinds of mine fire scenarios (Case 1 and Case 2) were numerically simulated and analyzed using FDS, a fire dynamics tool. Roadway passability coefficients was coupled with smoke hazard levels to establish the equivalent length calculation model for roadways. Incorporating smoke-related safety factors on personnel evacuation, the optimal evacuation paths were planned using the Dijkstra algorithm. Finally, evacuation simulations were performed using the Pathfinder software to validate the planned routes. Results show that: In two fire scenarios, the equivalent length of the optimal evacuation route and the shortest evacuation time for each working face have been quantified. In Case 1, the equivalent lengths of the optimal evacuation paths for each working face were 3 298.8 m and 956.9 m, with the shortest evacuation time being 1 595.8 s and 405.8 s, respectively. In Case 2, the corresponding equivalent lengths were 3 927.2 m and 2 332.4 m, with the shortest evacuation time of 1 364.8 s and 786.8 s. The calculated optimal evacuation paths match the Pathfinder simulation results, confirming the validity of this optimal evacuation path planning approach based on the equivalent length of the roadway. This method could be applied to the planning of evacuation paths in coal mine fires, which provides a theoretically innovative and engineering-applicable solution for the emergency evacuation in complex mine fire environments.