The nitrobenzene gas-phase hydrogenation reaction is controlled by the internal diffusion rate, so in order to effectively reduce the influence of internal diffusion, it is necessary to reaming the silica gel of the Cu/SiO2 catalyst used in the reaction. By adding sodium carbonate solution and ammonia aqueous solution to silica gel to reamb the pores, some rules of reaming were studied, and the Cu/SiO2 catalyst prepared by reaming silica gel was determined by copper content, pore volume, density and activity specific surface, so as to determine the optimal conditions for reaming treatment when preparing Cu/SiO2 catalyst: use sodium carbonate solution with a mass fraction of 0.67% as a pore reamer, reaming at 50 °C, and roasting at 500 °C for several hours.