Abstract: Based on an analysis of the formalas u-ed at home and abroad for calculating the critical velocity of blurry accumlalion in pipelines, the author presents a new one suitable for the full composition range: The coefficient and exponent values of minerasl lurry and cinder had deen worked out witb the samples in Laboratorytubes, within the common composition range (20%~65%) the comparative error between the critical flow velocity calculaled by using the formula in the paper and the actumeasured valued is ±30%, which can be used in engineering preliminery design.