Abstract: Non-monotonic characteristic curves of pressure drop in cyclone of a circulating fluidized bed (CFB) system were measured using transient-blowing method, while relationship between the cyclone pressure drop and solid mass flow studied under specific gas mass flow with corrected model based on cyclone pressure drop approach proposed by Chen. Meanwhile, the stability of CFB system with two cyclones in parallel was analyzed according to the law of mass conservation and constraint conditions as equality in pressure drop of all cyclones, and the least-energy principle, etc. Results show that with the rise of inlet solid mass flow, the cyclone pressure drop first decreases quickly and then increases slowly; the calculated values of cyclone pressure drop based on corrected model fit well with experimental results; when the cyclone pressure drop and circulating flow rate of CFB system are in deviation region, the CFB system will run stably in deviation flow state.