For better understanding the influences of solid phase properties on the performance of the expanded bed, the expansion and hydrodynamic properties of cellulose-stainless steel powder composite matrix with a series of densities was investigated and analyzed in an expanded bed. Two kinds of matrix particle diameter fractions, the small one (60-125m) and the large (125-300m), were used in the present work. In general, the expansion factors decreased obviously with the increase of matrix ensity. A linear relation between the mean density of matrix and superficial velocity at expansion factor of 2.5 was found for same series of atrices. The Richardson-Zaki equation could correlate the bed expansion and operation fluid velocity for all matrices tested. The theoretical prediction of correlation parameters (the terminal settling velocity Ut and expansion index n) was improved with the modification of equations in the literature. The residence time distributions were investigated to haracterize the hydrodynamic property in expanded bed. Compared with three evaluation factors (the height equivalent of theoretical plate, Bo number and axial distribution coefficient Dax), the results indicated that Dax is the best parameter to analyze the bed stability of expanded bed under various operation conditions and matrix properties. In addition, it was found that fluid velocity is the most essential factor to influence the hydrodynamic properties in the bed. A linear relation between the Dax and superficial fluid velocity for all matrices tested was established.