Polyethylene pipes (PE) have been widely used for various urban gas pipeline transportation engineering. With the increase of service life, the aging of PE pipes has become a safety issue of urban gas pipeline transportation. Therefore, a practical prediction method for predicting the residual lifetime of in-service aging polyethylene pipe is needed. Hitherto, there are a few reports on the aging performance and lifetime prediction of PE pipes under the laboratory research stage, but there are few researches on lifetime prediction methods of in-service aging polyethylene pipes. In this paper, aging PE pipes under different pressures and temperatures were produced by an accelerated aging test which was used by a thermal oxygen aging experimental set-ups PE pipes. Aging PE pipes were respectively tested by a tensile test, DSC and MFR (Melt Mass Flow Rate), and the test’s results of aging PE pipes were analyzed comparatively. Then, a residual lifetime prediction equation of pressured gas PE pipes was proposed by Arrhenius fit of the data which comes from the test’s results. Basing on this equation, a residual lifetime prediction method of aging polyethylene gas pipes in service was proposed, that is, the DSC test data of the particle (about 15 mg) which is cut from the surface of the in-service polyethylene gas pipes can be substituted into the lifetime prediction equation to predict the residual lifetime of aging polyethylene pipes. This residual lifetime prediction method is not only suitable for pressured aging polyethylene gas pipes in service, but also for other pressured plastic pipes in service.