Fluid flow, heat transfer and combustion in Jinlong CJD concentrate burner flash smelting furnace have been investigated by numerical modeling and flow visualization. The modeling is based on the Eulerian approach for the gas flow equations and the Lagrangian approach for the particles. Interaction between the gas phase and particle phase, such as frictional forces, heat and mass transfer, are included by the addition of sources and sinks. The modeling results including the fluid flow field, temperature field, concentration field of gas phase and the trajectories of particles have been obtained. The predicted results are in good agreement with the data obtained from a series of experiments and tests in the Jinlong Copper Smelter and the temperature error is less than 20 K.