In recent years, many accidents caused by alternating current (AC) corrosion have been reported. AC corrosion had become a serious potential damage to buried steel pipelines. X100 pipeline steel is very promising material for long distance gas pipeline, and the soil at Korla district is a kind of typical saline-alkali soil in the western China. The effects of AC current density (0~500 A/m²) on the corrosion behavior of X100 steel in an artificial solution, which simulated the soil medium at Korla district of the Xinjiang Uygur Autonomous Region was investigated by electrochemical test, immersion tests and surface analysis techniques. Results show that the average corrosion rate of X100 steel increases with the increasing AC current density. When the AC current density is below 100 A/m², the corrosion is uniform corrosion, while local corrosion occurred under a larger AC current density. The corrosion product of X100 steel under AC interference may be differentiated as two layers. The outer layer is a loose yellow product mainly composed of FeOOH, and the inner layer is a relatively dense and black product with cracks mainly composed of Fe₃O₄, which has almost no protectiveness to the substrate. At the beginning of AC interference, the corrosion potential of X100 steel in the simulated solution shifts negatively and the higher the AC density is, the potential shifts more significant, but as the AC density higher than 200 A/m², the corrosion potential shifts positively and then tends to be stable. The potentiodynamic polarization curve shows that X100 steel is actively dissolved in the test solution under AC interference, and the corrosion current density increases as the AC current density increases.