Abstract:  The drying of natural gas pipelines before production can prevent hydrate formation， pipeline corrosion and the fluidity of natural gas in pipelines. DF 13-2 subsea 24″ pipeline is 195 kilometers long， and the vessels need to complete offshore construction during typhoon and monsoon seasons， and the weather window for continuous operation is short. In order to complete the drying operation of the sea pipe as soon as possible in the operating weather window， the dry train composed of dry air， Desiccant and Gel is adopted to complete the fresh water desalination， pipeline drainage， pipeline purging and drying and other operations of the sea pipe at one time， so as to improve the operating efficiency. The size of the pig and the hardness of polyurethane were optimized， and the pig train was successfully collected. The abrasion resistance and tightness of the pig were tested， which could meet the requirements of longdistance pipeline drying.