The construction process of the cutter suction dredger will be stopped by the blockage of stone frequently,and the best way at present is to install anti-stone device in the cutter head.But there is no national standard for it.Different companies have developed different types of anti-rock devices,and there has been no quantitatively way to assess the impact of these devices on the suction capacity of the cutter suction dredger.This paper summarizes the form of commonly used anti-rock devices,uses CFD method to simulate the different flow field around the suction port between with and without installation of anti-rock devices,computes the hydraulic losses of the dredger when using different anti-rock devices,and determines the coefficients of hydraulic loss of different anti-rock devices.The result shows that the hydraulic loss of net anti-rock device and double ring anti-rock device is larger,and that of ring anti-rock device and staggered anti-rock device is the least.It provides the basic data for the selection of anti-rock devices.