According to the buried depth requirements of the crossing channel section of the subsea pipeline, the commonly used lowering methods are analyzed and compared, including newly built pipeline nearby and lowering the live pipeline. Taken the current situation of the pipelines and cables built in the nearby sea area, the water depth of the shipping channel, the seabed bottom soil and the pipeline parameters into consideration, the lowering and in-place stresses and the anti-floating evaluation are assessed. It is recommended to lower the live subsea pipeline by post-trench technology. Combining the ability of the post-trench equipment, adopting step-by-step implementation and layered excavation to lay down the live pipelines is comprehensively considered. The key parameters of the lowering construction are analyzed, and the specific implementation measures are given to provide reference for the implementation of the subsequent projects.