Abstract: Irregular shape catalysts with through-holes are new type catalysts developed recently. They are helpful to modify heat transfer character and to decrease the pressure drop of the fixed bed. This paper studied the influence of irregular shape catalysts with through-holes on the pressure drop of the fixed bed and determined the equivalent diameter of irregular shape catalysts with through-holes. The equivalent diameter can be obtained by determining the pressure drop of the fixed bed packed with a certain catalyst. Equipment used to determine the equivalent diameters of catalysts is established. The equivalent diameters of three irregular shape catalysts were determined by Ergun equation.