Most of natural gas from Boxi terminal is led into flare system and vented to the air after burning. Natural gas is a kind of clean and non-renewable resources, it is necessary to recover the vented gas for reusing. Conducted is analysis and review on vented gas recovery techniques at home and abroad and proposed is the method for vented gas recovery by using gas holder, which will not affect emergency relief of flare system. Application results show that this method is feasible and good benefit can be obtained by adoption of this method and it is suggested that such vented gas recovery technique is popularized and applied in other terminal treatment plants.