Polypropylene-palygorskite composites were prepared by melt mixing, using polypropylene as polymer matrix and palygorskite as inorganic components. The couple-agent modification of palygorskite was introduced in detail and the relation between structure and properties of polypropylene composites was mainly studied. The characterization on structure of polypropylene composites indicated that after modified by couple-agent，the dispersity of palygorskite in the polymer matrix was improved. The results showed that mechanical properties of composites were improved generally due to the addition of modified palygorskite. In addition, the optimum conditions of palygorskite modification for surface free energy of palygorskite and impact ductility of composites were deduced respectively by orthogonal range analysis.