Heihe Basin is the second continental river basin in china, having a wetland area of 170411.2 hm~2 in the middle region distribution, and water-land ecotone reed wetland of 30000 hm~2. It takes the reed wetland in the middle of Heihe River Basin as an example, and discusses the vertical variation of carbon in soil profile. The results show that bulk density of soil profile in 0-20 cm is lesser, and the mean is 0.365 g·cm~(-3). Soil bulk density sharply rises in 20-50 cm. Soil bulk density under 50 cm is gre...