Gas pipeline is the basis and guarantee of urban energy delivery, and hence accurate pipeline plane position and buried depth are important information for gas company operations management and the establishment of the GIS system. In recent years, due to the advantages of anticorrosion capability, PE pipeline has been widely used in medium and low pressure town gas transmission. As PE pipe is an inert material which is non-metallic, conductive, permeable, so it's difficult to determine its position in the underground space. In this paper, the authors analyzed the detecting principle and locating method of geological radar, studied imaging characteristics of PE pipeline in geological radar and the method for distinguishing steel pipe from cable, and investigated the inflection point, tee with casing, PE pipe. In addition, a method for determining the feasibility and accuracy of detection method was verified by the excavation. The research results have important significance in improving the detecting precision of PE pipeline as well as the gas pipe network information system.