This paper analyzed the error of coarse sediment concentration measuring in suspended load integrating method, according to velocity and distribution of sediment concentration. It was considered that the coarse suspended loads would be concentrated on the river bottom in view of sediment discharge or suspending height, which would lead to error of some measuring methods. The relative errors of various coarse grain measuring methods were also analyzed. The results show that the error will be bigger and bigger to inacceptable along with the particles getting coarser, which will appear during scouring in the lower reaches of reservoirs. For this reason, the concerned study should be made and the measuring methods should be regulated. It is proved that the con- clusion is credible in theory by contrasting the experiment results from the hydrometric stations of Shashi and Linli.