The key of soft foundation treatment for large oil tank is to control the settlement and differential settlement.However,the ordinary dynamic compaction replacement method has the problem that the replacement of the piers is in poor bottom condition and the settlement of the foundation after construction is large.Aiming at this problem,the improvement of ordinary dynamic compaction replacement method is studied.The preformed hole process can solve the problem of the poor bottom condition of the pier,so as to reduce the settlement amount of the foundation.The preformed hole dynamic compaction replacement method is a kind of construction technology which is used to deal with the weak soil foundation,which has the advantages of short construction period,low cost and green environmental protection.Through the preformed hole to guarantee the reliability of the replacement pier bottom,the settlement and differential settlement are successfully controlled.The actual test results and the water filling preloading test confirm the reliability of the treatment scheme.