Abstract: Traditionally,the iron-based catalysts for Fischer-Tropsch ( F-T) synthesis are reduced in an individual slurry bed reactor before being transferred to the main slurry bed F-T reactor. With the scale-up of F-T reactor,the matching slurry bed reduction technology exhibits the drawbacks of low production capacity and long reduction period.Through the study on the gas-solid fluidization characteristics of iron-based catalysts,the development of gas-solid flu- idized bed technology with high production capacity and low reduction period can significantly improve the economic profit of F-T synthesis plants. Based on the analysis of the physical properties of iron-based catalyst,the influence of process parameters on the fluidization characteristics are investigated in a high-temperature and pressurized stainless- steel gas-solid fluidized bed reactor using the mixture of H2 and N2 as simulated syngas. Specifically,the effects of tem- perature and pressure on the fluctuation of bed pressure drop as well as the impacts of temperature and superficial ve- locity on the gas-solid distribution in the reactor bed are examined,which is combined with the numerical simulation that reveals the influence pattern of superficial velocity and temperature on the axial / radial distribution of solid phase and axial distribution of particle velocity in reactor bed under pressurized condition. The transition velocity of the bed from bubbling state to turbulent state under elevated pressure is obtained and compared with that under atmospheric pressure. The experimental results indicate that the increase in pressure can lower the fluctuation of bed pressure drop. In addition,the bed would start the transition from bubbling state to turbulent state at 0. 26 m / s superficial velocity un- der 3. 0 MPa. The simulation results show that along radial direction,the particle concentration distribution generally presents a “core-annular structure” at different bed heights,while the particle velocity distribution displays a fast up- ward flow at the core area of the bed and a relatively slow downward flow near the wall. Moreover,the increase of tem- perature will also decrease the pressure drop fluctuation,while its effect on particle concentration and particle velocity distribution is insignificant. During the industrial operation,raising the pressure of the gas-solid fluidized bed properly may facilitate the formation of turbulent fluidization and improve the fluidization quality.