The Yellow River Delta is a typical area of continental shelf sedimentation under the interaction of land and sea, with a majority of sand and mudstone layers, poor stratigraphic cementation, and frequent interbedding of mud and sand.According to the actual coring situation, the sedimentary thickness reaches 1051.50m.Construction in loose and poorly cemented sedimentary rock formations in the long borehole section is difficult and risky; The drilling is located in the coastal wetland area, and there is no similar coring drilling as a reference. The construction has technical problems such as mud making in mudstone formations, water inflow in sand layers, leakage, dilution of mud, over diameter, and risk of hole wall collapse. At the same time, the technical requirements are to maintain the original state of the rock core. In response to technical difficulties, key technical methods such as cross caliber rope coring drilling tools, potassium based low solid polymer mud system, and water pressure coring were adopted, while also ensuring solid phase control and short lifting of mud. Cement sealing is used to ensure the sealing effect and safety of the sealing operation. Oil well cementing cement and water reducing agent are used to significantly increase the fluidity of the cement slurry and reduce the probability of sealing accidents without changing the water cement ratio. The successful completion of this drilling provides a reference for similar core drilling in sedimentary formations in coastal areas in the future.