Abstract: The conventional geometric parameters relevant to inclusions, i.e., aspect ratio and volume fraction, are unsuitable to the micromechanical study on inclusions if taking the coin-like crack as inclusions of which both the aspect ration and volume fraction approach zero. The fact has been verified via numerical exemplification. So, two other parameters are introduced to describe the geometric characteristics of cracked inclusions, i.e., the crack area fraction and the aspect ratio of representative volume element. Then, based on Mori-Tanaka method, the elastic modulus is calculated for a composite in which the unreinforced and fiber-reinforced matrices both contain the coin-like cracks as inclusions with different geometric parameters. The applicability of the two new parameters are verified with their effects discussed.