In this article,study on the aggregation structure of polypropylene (PP) material with IAS4 image analysis system was reported．The result indicated that the form of spherulite or filling particle in the matrix of crystalline polymer can be quantitatively described by IAS4 Image Analysis System．Through the measurement of aggregation structure,the transformation of mechanical properties can be explained．With the increase of filling quantity of nucleating agent,the spherulite size(Dn) and its distribution(Cd)tends towards decline．Under different heat treatment technology,Dn and Ca has little changed．It was showed that,with the decrease of Dn,the notch impact strength increase．To the PP／talc composite,the aggregation of talc panicle has relation with the original size of particle,filling quantity and the surface treatment level．With the decrease of particle size,the notched impact strength goes up．So,the image analysis is a kind of effective method to study the relationship between structure and properties of polymericmaterials.