This paper studies the nearshore wave,current and sediment movement after building a groin by the numerical simulation,discusses the selection of the groin length and its angle based on the analysis of the changes of the nearshore sediment transport rate and the nearshore current,and obtains the along-groin rip current and near-groin sediment movement with different slopes of beach,different wave heights and different wave directions,with suggestions on the selection of the length and angle of the groin recommended.