The exact prediction of both the melts flow and metal-bath interface deformation is critical to the design of commercial aluminium reduction cells which operate steadily at high current efficiency (CE). An inhomogeneous flow model of three phases, metal, bath and gas bubbles, was established in this study. The flow in a 300 kA cell was numerically computed with the model by using the finite volume scheme, and the results reveal the relation among the motion of the three phases and prove that the globality of the flow in cells could not be neglected. An improved calculation model of CE, based on the surface renewal theory, was also developed by connecting the melts flow with the mass transfer of reduced entity at the metal-bath interface. Using the model, the local CE in the 300 kA cell was predicted, and the calculated CE value of the whole cell is reasonable. (C) 2010 Elsevier Ltd. All rights reserved.