Integrated bubbling-transport fluidized bed is a potential reactor for CO 2 capture with solid sorbents. The gasparticle flows in the reactor greatly influence the capture efficiency. This paper studied the gas-particle flow behaviors in this reactor, focusing on the particle circulation and gas entrainment. The results show that the particle circulation rate is mainly limited by the particle-returning capacity of loop seals. Both the particle circulation rate and the gas entrainment rate increase with the total static bed height, fluidization velocity, and central gas velocity. The particle circulation rate is the most sensitive to the fluidization velocity, whereas the gas entrainment rate is the most sensitive to the total static bed height. When keeping the total static bed height constant, the particle circulation rate and the gas entrainment rate increase with the bed height of stage II. Synthesizing the above analysis, fine sorbents are recommended when applying this reactor for CO 2 capture with solid sorbents.