Abstract: Because the submarine gas pipeline in Panyue 30-1 Gasfield is characterized by a long distance and large diameter, therefore vacuum drying technique is chosen as the method to dry the pipeline in pre-commissioning stage. Four factors that will impact the vacuum drying time in pipe length, pipe diameter, nominated suction speed of pump and thickness of water film are analyzed and an optimization method is presented. For the pump optimization, the cost, construction progress, risk and other factors need to be considered before the determination of the pump. Water film thickness optimization adopts the dried air produced by drying machine as the propulsion medium for the spill sphere. The more desiccated the medium is, the better the effect will be. Considering power range of compressors and the capacity of the spill sphere trap, more empty spheres should be arranged and the travelling speed of the spheres should be limited. The vacuum drying practice shows the correctness of the drying prediction time and the existed experience will be a good reference for the similar projects in submarine vacuum drying technique.