In this study, Glass wool which is mainly applied to heat and acoustic insulation was used as reinforcement materials. The composite material samples consisting of glass wool, polypropylene, and maleic anhydride grafted polypropylene were synthesized and the tensile strengths were evaluated. The treatment of glass wool with 3-amino propyl triethoxy silane coupling agent together with epoxy film former enhanced the tensile strength of the composite samples including the glass wool and the tensile strength reached to the same level of the conventional composite samples including chopping continuous glass fiber. Therefore, we concluded that glass wool has a good potential as a reinforcing material in thermoplastic composites.