Regarding the beach protection belts in submerged type，we apply the method of combining theoretical analysis with the generalized flume test to study the diversion effect of beach protection belts in submerged type. The results show that the diversion beach protection belt has a good regulative effect on the water flow. The efficiency of the beach protection belts is expressed by the offset distance and the increase discharge of the main stream. The efficiency of the beach protection belts is affected by the water-blocking ratio and the submergence of the beach protection belts. The offset distance of the main stream and the rate of the offset discharge can well evaluate the efficiency of the beach protection belts.