The invention discloses a water proofing and leak repairing construction method for a sewage pipe network below the underground water level. The method is performed through the following steps that 1, sewage removal is performed on a pipeline; 2, leak points are found and marked; 3, a precipitation well is drilled, and precipitation processing is performed on a construction well point; 4, leaking stoppage is performed on the interior of the pipeline; 5, a grouting hole is drilled, and cement paste is backfilled and grouted. According to the method, a lining pipe does not need to be used, the construction cost is saved by 50% compared with the method that water proofing and leak repairing are performed on the sewage pipe network in a lining pipe mode, and the high application and popularization value is achieved; the actual available pipe diameter of the sewage pipeline cannot be reduced, and the phenomenon that the drainage capacity of the sewage pipeline is reduced due to water proofing and leak repairing cannot occur; by grouting on the exterior of the pipeline to form a grouting layer at the periphery of the sewage pipeline, the strata at the periphery of the sewage pipeline is reinforced, and effective protection on the sewage pipeline is formed to prevent formation stress from destroying the sewage pipeline.