Abstract: A second-order moment two-phase turbulence model for dense gas-particle flows (USM-Θ model), combining the unified second-order moment two-phase turbulence model with the kinetic theory of particle collision, was proposed. The interaction between gas and particle turbulence was described by using the transport equation of two-phase velocity correlation.The proposed model was used to simulate gas-particle flows in a horizontal narrow channel.Simulation results and their comparison with the experimental results showed that the predictions accounting for both particle turbulence and particle-particle collision were obviously better than those accounting for only particle turbulence or only particle-particle collision.