In the drilling process of offshore exploration wells and high-risk wells, the possibility of high-pressure overflow and kick increases greatly when encountering unknown or inaccurate formation conditions. If it is not handled properly, it may cause catastrophic accidents. Overflow and kick are the early warnings of blowout accidents, and the wellhead blowout preventer can be shut off first to cope with such emergency conditions. However, once the bottom hole high pressure spreads to the wellhead, it may bring safety risks to the wellhead emergency disposal. In this work, a new type of downhole packer while drilling was designed to quickly seal the annulus when high-pressure fluid appears underground. ABAQUS software is also used to simulate the sealing performance of the rubber cylinder, and analyze the stress changes of the rubber cylinder during the setting process. When the working stress is 10MPa, the maximum Mises stress of the rubber cylinder is 14.3MPa, and the contact stress of the rubber cylinder presents a “shoulder protrusion” distribution. By comparing the stress changes in the rubber cylinder with or without a metal skeleton, it was found that the overall contact stress with a metal skeleton will increase, which has a good impact on the sealing of the rubber cylinder.