At present most of middle and low pressure fuel gas pipelines in the underground adpot PE pipe material, and the excavation laying construction technology. Because in the laying process, there are obstacles or municipal government doesn't allow excavation, direct excavation laying can’t be carried out.The current pipeline laying is orientation crossing (trenchless). The emphases and difficulties in the construction technology and construction process were analyzed,the importance of signs of pipeline and completion data were emphasized, the orientation crossing of pipelines was analyzed by several instruments. It is proposed that the RD8000 and the ground penetrating radar can be used for the detection of pipelines under the condition of good tracing line.  The most accurate detection of the pipeline can be intuitively detected by high precision pipelineand when the conditions of the excavation, stopping gas, opening hole have been met.