In recent years，the development of cutter suction dredger gradually develops to environmental protection and green energy saving，and the anti-diffusion technology is the core of the development of environmental protection cutter suction dredger.In this paper，the prototype environmental protection reamer is further reformed by adding movable flaps on both sides of the reamer cover to flexibly adjust the cutting depth and suction concentration of the reamer.The CFD (Computational Fluid Dynamics) software is used to simulate the prototype reamer and the new reamer，and the flow field on both sides of the reamer is compared in the cutting process.The results show that the diffusion prevention effect of the new reamer is obviously better than that of the original reamer.From the perspective of structure，the cutting depth of the new reamer is flexible and adjustable，which can meet the requirements of different field conditions，and provide a certain theoretical basis for the subsequent construction of economic and environmental protection cutter suction dredger.