Abstract: Rubber flexible pipes have been increasingly used in seismically isolated buildings. Whether it could work normally after the earthquake directly affects the function of the building. The vertical rubber flexible pipeline is selected as the research object. Base on the deformation requirement of 400 mm, the seismic performance test is carried out considering the influence of two nominal inner diameters and four different design lengths. The seismic damage evolution model, deformation and bearing capacity characteristics of this type of pipeline are compared and analyzed. The test results indicate that: The pipes with smaller design length cannot meet the expected deformation target. Such pipes experienced two key states： pipe stretching and single-sided fracture. And such pipes must be replaced after the earthquake; For pipes with a design length consistent with the code recommendations, deformation requirements can be met; The quantitative relationship between the nominal inner diameter and design length of the pipeline and its horizontal deformation ability was obtained through regression analysis; For pipes with an identical design length, the nominal inner diameter of the pipeline and the horizontal ultimate load at the time of failure are positively related. Meanwhile the ratio of ultimate load for the pipe with a large and small nominal internal diameter is smaller than the ratio of correspond inner diameter.