A model to describe the solids flow under blast furnace conditions with countercurrent gas flow is developed on the basis of fluid mechanics and the principles of solid mechanics. The surface stress resulting from the interaction among flowing particles is considered to be composed of two parts: rate-dependent and rate-independent. The concept of viscosity is extended to solids flow to represent the hydrodynamic particle-particle interaction (rate-dependent part), and the concept of solid plastic modulus and Coulomb frictional stress relation are employed to describe the frictional contact interaction (rate-independent part). Moreover, a method is proposed to determine the transition between moving and non-moving zones, i.e. the profile of stagnant zone. The validity of the model is demonstrated by the good agreement between the model predictions and measurements obtained from a cold physical model of a blast furnace under various flow conditions.