Number of soil microorganism and enzyme activity and their relationship with soil nutrients were studied during subalpine coniferous plantation rehabilitation in western Sichuan. The results showed that the number of soil microorganism, enzyme activity of the mature spruce plantation were significantly lower than those of the young spruce plantation and secondary broad-leaved forest. Soil fertility degraded greatly with increasing of spruce plantation age, which was mainly affected by forest micro-environment. There were significant correlation between the amounts of soil microorganisms and soil enzyme activities and soil organic matter, total N, total P, alkali-hydrolyzable N and available K. Therefore soil biological index can be used as evaluation index of soil fertility. Inorder to accelerate the course of plant restoration and rehabilitation, the strategy and measures were put forward, including application of thinning rationally for existing dense plantations and establishment of mixture forest of coniferous and broad-leaved trees for new plantations, which would create good forest micro-environment for plant growth.