Complex and variable nature of the river sediment yield caused many problems in prediction of the long-term sediment yield and input into the reservoirs. Sediment rating curves generally used to estimate the suspended sediment load of the rivers and drainage basins. Since the regression equations of the sediment rating curves obtained by logarithmic retransformation and have a little independent variable involve in this equation, they also overestimate or underestimate the true sediment load of the rivers. In order to evaluate the bias correction factors in Kalshor and Kashafroud basins, 7 stations of this region with suitable upland area and spatial distribution were selected. Investigation of the accuracy index (ratio of estimated sediment yield to observed sediment yield) and the precision index of different bias correction factors of FAO, QMLE, Smearing, and MVUE with LSD test show that FAO coefficient in all of the stations increase the estimation error. Application of MVUE in Linear and Mean load rating curves has not statistically meaning full effects. QMLE and Smearing factors increased the estimation error in mean load rating curve but have not effect in linear rating curve estimation.