Abstract: The corrosion property of carbon steel has been investigated by the buried coupons along the natural gas pipeline in Beijing. The corrosion products has been analyzed by x-reaction. The corrosion morphology of the bare steel coupons can be-divided into the general corrosion and localized corrosion including ulcer spotting and round hole. Except for inclusion in material, the corrosion behavior is related to the physical-chemical property and the structure of soil. The soil is a complicated medium for its polyphase, porous, in-homogeneous and the complex of inter relationship among parameters, so the corrosion property of the carbon steel coupons is the result of cooperating action of many parameters.