Abstract:The soil microbial community diversity at different soil depths (0-20 cm, 20-40 cm, 40-60 cm) was analyzed by phospholipid fatty acid (PLFA) method in coniferous forest and Schima superba plantations in Heshan, Guangdong Province. The results showed that the amounts of total PLFAs, bacterial PLFAs, fungal PLFAs, Gram-positive bacterial PLFAs and Gram-negative bacterial PLFAs were the highest at 0-20 cm soil layer and decreased with increasing soil depth; the total PLFAs in Schima superba plantation was higher than that in coniferous forest, and was positively correlated with soil organic carbon and total nitrogen in the plantations. In the same soil layer, the concentration of bacterial PLFAs was higher than fungal PLFAs. Principal component analysis (PCA) indicated that the variation in soil microbial biomass and community structures were influenced by the differences of plantations and soil depth, PC1 was mainly composed of fatty acids of i13:0、a13:0、17:0、cy17:0 and 16:0, and PC2 mainly composed of i16:0、cy19:0、18:1ω9c、i15:0、18:2ω6c and a17:0.