Eight representative soil profiles were installed on three types of wetland (two profiles on Carex spp. -dominated floodplain, four on Phragmites-dominated floodplain, and two on paddy soil) in Dongting Lake floodplain of China in 2004, and their C, N and P contents, microbial biomass C, N and P, <0.001 mm clay particles, and bulk density were measured. The results indicated the spatial distribution of soil C and N and soil microbial biomass C, N, and P were very similar in the profiles (0-100 cm) of three types of wetland, being decreased gradually with depth, except for soil TP which was constant in the profiles. The percentages of soil microbial biomass C, N and P to soil organic C, total nitrogen and total phosphorus decreased gradually with depth. In top layer (0-10 cm), the contents of soil organic C and microbial biomass C and the percentage of soil microbial biomass C to organic C were 19.63-50.20 g x kg(-1), 424.63 - 1 597.36 mg kg(-1), and 3.17% - 4.82%, respectively, the contents of soil total N and microbial biomass N and the percentage of soil microbial biomass N to total N were 1.85-4.45 g x kg(-1), 57.90 - 259.47 mg x kg(-1), and 3.13% - 6.42%, respectively, and the content of soil microbial biomass P and the percentage of soil microbial biomass P to soil total P was 24.16 - 200.99 mg x kg(-1) and 1.09% - 11.20%, respectively. The bulk density of soil top layer (0 -10 cm) was 0.65 - 1.04 g x cm(-3), and the content of < 0.001 mm clay particles was 26.24% - 39.48%. The contents of soil organic C and N and microbial biomass N and P in 0 - 10 cm layer were the highest in Carex spp.-dominated floodplain, followed by paddy soil, and Phragmites-dominated floodplain. Also in 0 - 10 cm layer, the soil microbial biomass C in Carex spp. dominated floodplain and paddy soil was higher than that in Phragmites-dominated floodplain, while the soil bulk density in Phragmites-dominated floodplain was higher than that in paddy soil, and much higher than that in Carex spp. -dominated floodplain. The amount of soil < 0.001 mm clay particles in Carex spp. -dominated floodplain and Phragmites-dominated floodplain was higher than that in paddy soil. In these three types of wetland, soil organic C and N and microbial biomass C, N and P had a significant logarithm correlation (P < 0.01) with <0.001 mm clay particles, and a significant index correlation (P <0.01) with bulk density.