Abstract: Several important principles for designing the structure of the gas-solids entrance for the circulating fluidized bed down-flow reactor(downer)were proposed based on summarizing the existing investigations.A new entrance structure based on strong turbulence dispersion was designed and tested on a semi-industry downer cold model with 418mm I.D. and 18m height.Inside this new type downer entrance, a strong turbulent flow field, which was introduced via the impinging of high velocity gas flows in opposite directions,could make the gas and solids mix well quickly.The gas-solids flow and mixing behavior inside the entrance as well as in the downer main bed were studied by using the dual-optical density probe, Laser Doppler Velocimeter (LDV), micro-manometer and the steady state hydrogen tracing technique.Results showed that compared to the traditional downer entrance structure based on the jet flow from single-tube or multiple-tube, although there was no gas-solids distributor for this new downer entrance, it could quickly make the gas-solids flow with high flux rate be well distributed, indicating that this downer entrance could be a potential excellent entrance for industrial downer reactor.