Due to the large depth and weak signal of the trenchless construction method, it is difficult to accurately detect the pipeline on the water surface. Through practical research, by arranging detection points reasonably and fitting analysis of the results, the electromagnetic vertical section method can obtain the accurate spatial information of the target pipeline safely and effectively by using the blow drilling method. In this paper, the detection of a river crossing power pipeline in the Pearl River is taken as an example. Although the target pipeline signal cannot be acquired on the water surface, the electric cable buried more than 24 m still being detected with high precision by this method. The detection principle, implementation scheme and operation experience of this method can provide references for the detection of deep river crossing pipelines in navigable waters.