Abstract: The biodegradable composite films were prepared from corn stalks cellulose microcrystal(CSCMC) as the filler and poly(lactic acid)(PLA) as the polymeric matrix. The crystallinity, the tensile properties and the thermal properties of the composite flim were tested. The results show that the tensile properties and the thermal properties of the CSCMC/PLA composite were improved by the addition of corn stalks cellulose microcrystal. When the mass fraction of CSCMC is 10%, the initial decomposition temperature increases by 34.38 ℃, the tensile strength increases by 58.3% and the elongation at break increases by 31.1% compared to that of the pure PLA.