Abstract: Based on the analysis of the incipient standard, incipient probability and exposure degree of the uniform particles lying on the surface of the river bed, the formulas to calculate the incipient condition of uniform grains on different bed slopes are put forward by using the rolling balance mode, and the calculation parameters of incipient shear stress are presented. The comparison results show that the calculated values of the incipient velocity transforming from the incipient shear stress are in good agreement with those of experimental measurement.