A test device for sealing performance of packer rubber cylinder was designed and developed.The device can simulate the harsh conditions of 350 ℃ high temperature and 20 MPa high pressure under the oil well,can simulate the setting process of the packer rubber cylinder,and can detect the sealing performance of the packer cartridge.The sealing device of different types of rubber cylinders was tested by means of the test device,the pressure changes in the ring cavity of different packers in different media were measured,and the deformation state and corrosion damage of the packers were obtained.The sealing performance of each type of rubber cylinder under high temperature and high pressure conditions was examined.It provides a reliable test basis for the design and improvement of the packer cartridge.