Abstract: The convection heat transfer of air-coal powder mixture flow inside a horizontal tube under the condition of constant wall temperature was simulated and investigated experimentally. The simulation results showed the total heat flow rates of wall and wall to coal powder decreased with increasing of the solid powder diameter and increased with increasing solid volume rate while there was less influence of powder diameter and volume of solid on the heat transfer flow rate from wall to air. The Nusselt number of convection heat transfer increased with increasing the Reynolds number especially for large Reynolds numbers, and linearly changed with the solid volume rate. The correlation of Nusselt number of gas-sold two phase convection heat transfer obtained from numerical simulation was well consistent with the experimental result.