Calcium carbonate (CaCO3) of which the surface was pretreated with maleic anhydride (MAH) to introduce double bond groups, was grafted with polypropylene wax (PPW) via solid phase grafting in-situ to prepare modified CaCO3 with different chemical grafting efficiency of PPW. The contact angles of PP and different CaCO3 were tested. The surface energy, interfacial tension and adhesion work were calculated. The effects of these factors on the interfacial adhesion of CaCO3/ PP and mechanical properties were researched. The results show that the tendency of interfacial interaction between CaCO3 and PP as well as mechanical properties of the composites is the same as that of the ratio of their adhesion works to interfacial tension. This result is consistent with the sequence of interfacial interaction obtained from dynamic mechanical measurement. Thus the ratio of adhesion works to interfacial tension between CaCO3 and PP can be used as an important parameter to measure interfacial interaction and mechanical properties of the composites, which provide the scientific criterion to select and modify fillers.