The influence of operation parameters on the adsorption performance of protein (bovin serum albumin, BSA) in an expanded bed was studied using Streamline diethyl aminoethyl (DEAE). The result of residence time distributions (RTD) and breakthrough curves showed that adsorption performance of the expanded bed could not be improved by increasing the flow velocity at the range from 16 ml.min(-1) to 26 ml.min(-1). The increase of protein concentration from 0.5 mg.ml(-1) to 2 mg.ml(-1) resulted in poor adsorption performance. With increasing temperature from 5 degrees C to 30 degrees C and the sedimented bed height from 11.5 cm to 22.5 cm, the adsorption characteristics in the expanded bed were improved.