Abstract: Bankfull discharge at reach scale possibly contains the influence of various factors in a river reach and hence it is a better representative of the whole reach. This study has estimated such a bankfull discharge and the corresponding bankfull stage using a convergence method and WOL method based on morphological criteria respectively. The bankfull discharge and the convergence river length were estimated from the geometry data of the Inner Mongolia reach of the Yellow surveyed in the years of 1962, 1982, 1991, 2000, and 2004. Analysis shows that the river length for estimating the bankfull discharge at reach scale was increasing from 1962 to 2004. Other influence factors were also examined, including the definition of main channel and the averaged spacings of cross-sections and subsections. It reveals that the definition of main channel could be a significant factor in estimation of bankfull discharge.