Abstract: 2 active soil organic carbon fractions of microbial biomass carbon (MBC) and water-soluble organic carbon (WSOC) were selected, and active soil organic carbon fraction content characteristics and its influence factor of Abies fargesii forest in different altitude gradients were analyzed. The results showed the MBC and WSOC content increased with the altitude increase, and decreased with the deepening of soil. The MBC ranges from 0.30 g/kg to 1.22 g/kg at different altitude ranging from 2 200 m to 3 000 m, and the ratio of total organic carbon ranged from 1.05% to 2.09%. The WSOC ranges from 0.16 g/kg to 0.69 g/kg, and the ratio ranges from 0.57% to 1.20%. The 2 active soil carbon fractions content are all showed high positively correlation with total soil organic carbon content, total N content and soil moisture(P < 0.01), while appeared high negatively correlationwith soil temperature(P < 0.01). Total soil organic carbon content is the decisive factor affecting active organic carbon fractions content. And two active soil organic carbon fractions were also appeared high positively correlation.