Abstract: At present, research on mine belt fires mainly focuses on the distribution characteristics of the temperature field, the evolution of smoke concentration, and the quantification of critical wind speed in straight roadways. However, there is still a lack of systematic investigation into the coupling characteristics of temperature field, CO concentration, visibility, and critical wind speed in the interconnected layout of the main transportation roadway and the auxiliary connecting roadway, which makes it difficult to provide comprehensive support for safe evacuation and ventilation control in complex belt fires. To address this problem, a fire simulation model was established using Pyrosim software. Visibility, temperature, and CO sensors were installed at different positions and heights to explore the dynamic evolution of fire-related environmental parameters such as CO concentration, temperature, and visibility in the main transportation roadway and the auxiliary connecting roadway. The study also revealed the dynamic coupling mechanism between harmful gas diffusion and environmental parameters within roadways during belt fires. The results showed that the roadway wind speed had a significant impact on the direction and speed of smoke spread. The critical wind speed for the simulated fire source was 2.5-3.5 m/s. When the roadway wind speed was low, a large amount of smoke was generated and accumulated due to incomplete combustion of combustibles. When the wind speed was lower than the critical wind speed, smoke backflow occurred. At a wind speed of 1.5 m/s, the maximum CO volume fraction and temperature appeared on the windward side, reaching 1 515.5×10⁻⁶ and 143.5 °C, respectively, and the proportion of low visibility was also highest at this wind speed. Smoke backflow could be completely suppressed when the wind speed exceeded 3.5 m/s.