In the design of hydraulic vertical piping lifting system for large-size particle material, the accurate determination of minimal transporting velocity of the lifted solid-liquid mixture is of importance to both preventing the blocking in piping and ruducing the power consumption. A new test method is presented in this paper. By using this test method, the floating velocity of the particles in a vertical piping can be derterminde. The dertermined floating velocity was used to determine the minimal transporting velocity of the test larg-size particles in vertical lifting piping. The empirical formula used for calculating minimal transporting velocity of the large-size particle material in some particle size and volume concentation ranges is presented. This method can be widely used to determine the minimal transporting velocity of other large-size particle material in the hydraulic vertical lifting piping.