Abstract: Based on fire dynamics principles, we investigate the combustion characteristics of fuels and the heat radiation transmission mechanisms of smoke in forest fire. Key combustion parameters for three common tree species in North China（Pinus tabuliformis,Sophora japonica,Populus davidiana）were measured using a cone calorimeter. A three-dimensional combustion numerical model was constructed with PyroSim software to analyze the effects of wind speed, ambient relative humidity and canopy structure on smoke heat radiation transmi- ssion. The results indicate that when wind speed is below 6 m/s, thermal radiation intensity increases with wind speed; however, when wind speed exceeds 6 m/s, enhanced turbulence restricts smoke plume diffusion, reducing thermal radiation intensity by 12%~16%. For every 15% increase in ambient relative humidity, thermal radiation intensity increases by 0.5%~1.6%, though this enhancing effect exhibits significant spatial heterogeneity. Canopy structure alters local turbulence intensity near the trees, leading to notable differences in thermal radiation intensity distribution. The findings provide theoretical support for understanding heat transmission mechanisms in forest fires and offer scientific references for optimizing firefighting tactics.

Key words: thermal radiation, wind speed, humidity, canopy structure