Abstract: In this study, the influence of plant aspen flower extract on the properties of cassia gum（CG）/sodium carboxymethyl starch（CMS） composite film was investigated. CG-PA-S films were prepared by using CG/CMS as film-forming matrix, glycerin as plasticizer and plant aspen flower extracts mixed with different mass fractions, and these films can be used in food packing. The effects of the addition amount of PA on the structure, mechanical properties, barrier properties and oxidation resistance of CG-PA-S films were mainly investigated, and then compared with the biomass films studied in other literatures. The results showed that when the mass fraction of PA was 6%, the composite film had better performance parameters, with the mechanical strength of 26.16 MPa and the elongation at break of 46.07%. With the increase of PA content from 0% to 6%, the oxygen permeability coefficient increased from 2.64×10^-12 cm~3/（mm~2·d· Pa） to 3.11×10^-12 cm~3/（mm~2·d· Pa）, the total phenol content in 50% ethanol increased from 0.104 mg/g to 0.582 mg/g, and the ABTS+ free radical clearance rate increased from 24.33% to 87.83%.