In this paper, the velocity distribution of secondary currents and their effects on suspended sediments concentration are discussed. The analysis of sencondary currents was developed on the basis of streamwise mean vortex equation by using non-slip condition as boundary condition. The theoretical curves show a fairly good agreement with experimental results. The spanwise variation of suspended sediments concentration in a open channel flow with stable secondary currents was clarified to maintain the similar form from experimental data and the information made the theoretical analysis easy. The theory predicted the spanwise undulation in suspended sediment concentration and it's vertical distribution in both upflow and downflow regions.