There are the unfavorable conditions in an old wharf renovation project in Tanga Port,Tanzania,such as deep and soft peaty foundation,limited renovation space,and the serious damage of the old wharf.The high piled wharf structure combined with rear sheet-pile for shore connection is adopted,which is suitable to the deep and soft peaty soil foundation.The high pressure jet grouting pile technology is used to reinforce the wharf slope,which ensures the safety of wharf structure.The internal and external stability of cement-soil piles are checked by Plaxis 3D three-dimensional finite element numerical analysis method.In view of the problem that it is difficult to control the forming quality of high-pressure jet grouting piles in high organic content soil,measures such as reducing slurry pressure,using repeated spraying technology,reducing water-cement ratio,and adding gypsum are proposed to improve the quality of jet grouting piles.