Abstract: The surface combustibles at forest fire sites of young forest of pinus yunnanensis were collected, and laboratory experiments on samples were carried out mainly by the iron combustion bed. The results showed that: the fire intensity generated by the burning of surface combustibles in the young forest of Pinus yunnanensis is low. Flame heat radiation, spread rate, flame height, flame maximum temperature, flame holding time and fire intensity are (2.71±0.74) kW/m², (0.41±0.11) m/min,(37.10±15.52) cm,(462.90±60.26) ℃,(4.24±1.07) min and (185.31±131.53) kW/m, respectively. The heat radiation and temperature during flameless combustion are (2.40±1.52) kW/m² and (325.00±64.97) ℃, respectively. The blocking time of the young forest of Pinus yunnanensis is about 100 s. The temperature at 30~150 cm away from the flame shows a sharp decline after a sharp rise in 30~133 s, and there is only one peak. The time to maintain high temperature at 10 cm away from the flame is long, the fire hazard of such fire is large, and more attention should be paid to prevent reignition when extinguishing.

Key words: the young forest of Pinus yunnanensis, fire sites, surface combustible, flameless burning, flame