The suction performance of the cutter greatly affects the construction efficiency of the dredging project.It is great significance to study the internal flow characteristics in the cutter to improve its suction performance.We use the computational fluid dynamics (CFD) method of the Reynolds-averaged Navier-stokes(RANS)turbulence model to simulate the internal flow of the two kinds of cutter with or without groove design on the cutter blades,and carry out the comparison and analysis of the internal flow characteristics of the two kinds of cutter to verify the reasonable and excellence of the groove design,which can provide technical support to optimization design of 5 000 kW rock cutter.