Since the vacuum potassium carbonate desulfurization was put into operation in Hansteel Coking Plant, the blockage of acid gas pipeline has seriously affected the desulfurization production. Therefore, the high pressure water gun flushing method and the hot alkali solution dissolution method were used to clean the acid gas pipeline. By comparing the two methods, it is concluded that the hot alkali solution dissolution method has more advantages of simple operation, no danger and no pollution risk of the cleaning solution.