Abstract: A simulation method of dense particle-gas two-phase reacting flow in the mixed Eulerian-Lagrangian approach is proposed, and the comprehensive model covers the two-phase turbulent flow, heat transfer and chemical reactions. The model is used to numerically study two-phase reacting process in a circulating fluidized bed. Detailed results on cluster structure, cluster size, particle volume fraction, gas velocity and particle velocity are obtained. The simulation results are reasonable, and are in agreement with experimental ones. It is concluded that the model and algorithm are feasible and can be used to study the dense particle-gas two-phase flow efficiently.