Abstract: Corrosion behaviors of X70 steel in the environments of Ku'erle soil corrosion station, soil saturated with water and simulated soil solution were studied by means of macroscopical observations, SEM, EDS, XRD, weight-loss method etc. The results reveal that the ranking of corrosion rate from the biggest is simulated soil solution, Ku'erle field soil, and soil saturated with water. It can be explained that the occurrence of microbiologically influenced corrosion leads to a high corrosion rate of X70 steel in Ku'erle field soil. In soil saturated water, water reduces the permeability of air, and soil blocks the ion exchange of X70 steel, which result in a low corrosion rate. In simulated soil solution, electrochemical reactions are easiest to take place, so the corrosion rate is the highest.