Taking the water diversion project of Zhougong Mansion,Kyaukkou Reservoir and urban water supply ring network project in Ningbo City as an example,this paper introduces the key points and difficulties in the design of laying DN2600 large-diameter PCCP pipe in soft soil foundation,especially for the loose leakage of PCCP pipe interface caused by some emergencies,introduces a kind of internal repair of lined steel pipe,which can meet the requirements of sealing and waterproofing,and can avoid excavation affecting the surrounding environment,and is convenient for construction,which is a feasible repair method for repairing and repairing the leakage of PCCP pipe interface leakage.It can be used as a reference for similar projects.