The mechanical and thermal properties of polypropylene (PP)/muscovite/ low-density polyethylene (LDPE)/ polypropylenegraftmaleic anhydride (PP-g-MAH) ternary composites were investigated. In PP matrix, muscovite, LDPE, and PP-g-MAH were added as strengthening agent, toughening agent, and compatibilizer, respectively. The effects of dosages of the added materials were analyzed. The experimental results show that the optimum recipe of PP/muscovite/LDPE/PP-g-MAH composites is100/10/6/20 (mass ratio). Compared with the pure PP, the mechanical properties of PP/muscovite/LDPE/PP-g-MAH composites, including notched impact strength, Rockwell hardness and flexural strength, are improved. Although tensile strength is slightly decreased, they have better toughness. Filled with muscovite, the heat-resistance and heat-decompostion of the composites are improved.