Taking Shuangjian shoal in Fujiang shoal reach as a study case,we analyze the formation cause and distribution law of the beach flow of Shuangjian shoal by the prototype observation data analysis and mathematical model method,and probe into its impact on the deepwater channel.The results show that in the ebb tide,due to the gradual weakening of the flow capacity below Zhanchun port in Fubei channel,the flow entering Fubei channel crosses over Shuangjian shoal beach face gradually and enters Liuhai shoal reach;while in the flood tide,flow in Liuhai shoal reach crosses gradually over Shuangjian shoal beach and enters Fubei channel.The size and intensity distribution of the beach flow relates mainly to the upstream inflow and the terrain conditions of Shuangjian shoal beach， i.e.,the beach flow moves downward in the floods and upwards in the low water.The beach flow with great intensity is unfavorable for Shuangjian shoal beach face’s stability,and the transported sediment due to scouring is disadvantageous for the maintenance of the adjacent channel depth condition.