Compared with the conventional caisson pier structure,a new type caisson with flange slab can effectively improve the wave reflection,decrease earth pressure behind the wall,and reduce the engineering investment.There are some practical engineering cases in comb-type breakwater while the caisson with flange slab is rarely used in vertical pier structure which has backfill in the rear.This paper introduces the application of caisson with flange slab in Dalian Songmu island general cargo pier,analyzes the effect of wave and wall backfill on comb-type pier structure,and studies the selection of flange slab caisson scale.