Abstract: Catalytic activity of Ni/SiO2 catalyst on combination of CO2 reforming and partial oxidation of CH4 using fluidized bed reactor was investigated. Effect of Ni loading, prereduction and reaction temperature were studied.The results indicated that the supported Ni catalysts deactiviated rapidly in 6 h on stream though it had high initial activity. By TG, XRD, TPR and TEM techniques, the Ni particles agglomeration in high temperature was responsible for the distinct decrease of activity.