The combustibility of four conifer-tree species in Xiaoxing’an Mountain, Heilongjiang Province was studied by cone calorimetric analysis. The four species were Pinus koraiensis Sieb.et Zucc、Pinus sylvestris var.mongolica Litv、Picea koraiensis Nakai、Larix gmelinii Rupr.. The thermal characteristics of leaves and barks, including smoke production rate(SPR)、specific extinction area(SEA)、the concentration of carbon dioxide (CO2)、the production of carbon dioxide ( PCO2 )、the concentration of carbon dioxide (CO)、the production of carbon dioxide ( PCO )were tested and recorded simultaneously.Th results showed that ,at a heat reflux of 50 kW•m-2, the values of SPR , SEA , the concentration of carbon dioxide (CO2) and the production of carbon dioxide (PCO) of Larix gmelinii Rupr. t had strong smoke inhibiting effect. Both Larix gmelinii Rupr. and Pinus koraiensis Sieb.et Zucc had strong smoke inhibiting effect, and Larix gmelinii Rupr. and Pinus koraiensis Sieb.et Zucc was most recommended as fire resistance species for fire-preventing forest belts.