Abstract: For the purpose of ensuring the normal operation of river-crossing pipeline, it is necessary to detect the burial depth periodically. In view of the inaccurate result caused by unstable electromagnetic signals during the detection of directional drilling crossing pipeline due to its large covering, the One-Pass underwater pipeline inspection system was optimized by changing the calibration method of electromagnetic signals in the crossing pipelines with different buried depth to improve the detection accuracy of directional drilling crossing pipeline. The consequences show that the higher degree of compliance of the results calculated according to the calibration data of the optimized electromagnetic signal with the actual situations indicates that the optimized One-Pass inspection system can satisfy the detection requirements for laying status of the directional drilling crossing pipeline within a water depth of 40 m. The research results could be used to guide the detection of the laying status of river-crossing pipeline by directional drilling, and they are of important significance to ensure the safety operation of river-crossing pipeline.