Abstract: After the operation of single cavern gas injection and withdraw in existing brine-extracted caverns of Jintan cavernunderground gas storage, and before being put into normal operation, the ?114.3 mm pipes only used for brine discharge need to betripped out. This can keep the gas injection/production pipe unobstructed and injection/production capacity meeting the need, and flexiblecontrol of downhole safety valve under emergency situations. Due to the unique cavity, casing program, string structure and higherwellhead pressure of the well（cavern） in Jintan cavern underground gas storage, we decided to use snubbing unit for tripping out the?114.3 mm pipe for one time. This unit has lifting and transportation capacity, and depends on the coordination of workover rig, auxiliaryequipment and bridge plug or blanking plug to realize tripping in/out with pressure. No-killing operations in 5 wells achieved success rateof 100% in Jintan cavern underground gas storage, providing technical support for similar big diameter pipe trip out.