OMMT was compounded by MMT and 1% (v/v) acetic acid dissolved chitosan via solution intercalate method, and then prepared the composites with epoxy resin. The change about spacing of montmorillonite was tested by XRD, and the molecular structure of OMMT was tested by Fourier infrared spectrum. The tensile strength and impact strength of epoxy resin composites were also tested. The result showed that the spacing of montmorillonite first increased then decreased along with the increasing mass fraction of chitosan. The maximum value (d001=1.983 nm) appeared when mass fraction of chitosan was 30%. And tensile strength and impact strength were improved by 86.8 and 51.2% respectively.