Aiming at the problem that sea sand and river sand used for backfill behind caisson structure of gravity wharf are relatively expensive due to strict environmental protection policies and backward mining methods in some overseas countries,we apply the field test to study the construction technology of rapid compaction in depth,propose the design and construction scheme of using low-cost material from mountain with a certain mud content as the backfill material,verify the feasibility of the technology by field test,and give the best number of ramming,the safe distance of ramming and the corresponding isolation treatment measures.The results show that the rapid compaction technology can be used for backfill behind caissons of gravity wharf,which can greatly reduce the engineering cost.