Dropped quantity of prawn (Penaeus orientalis) caught by drift netwas studied in a whole course of fishing operation. The net used was designed ba-sed on the structure feature of prawn drift net and the net had the function bothof catching prawn and receiving dropped ones. The survival rate of prawn whichdropped from the meshes of drift net was also studied. 1. In the whole course of menually hauling drift net on board the small boat of12 hp., the drop rate of prawn accounted for 40-74% of the total number of prawncaught in one haul. And the drop rate of 13-33% was reached in the course ofmechnically hauling on board of the large boat of 120 hp. 2. Through simulating test,it was found that the survival rate of prawn,whichwere picked up from a drift net by hand and cultured for 24 hrs,reached a level as high as more than 93%, while the immediate mortality of prawn found in net wasbelow 8%. There were a considerable number of scarred prawn appeared in the catch bydrift net, and it has proved that the dropped prawn could survive and enter intorecruitable population. The above results provide some scientific information for regulating the fishi-ng structure in the autumn season in Bohai Sea, and making management stra-tegy of gradually replacing prawn trawling by drift net operation.