The research on cassava starch improving properties of carboxymethyl cellulose films was studied.The results showed that the TS and water solubility of the composite films decreased gradually,while E and the transparency of the composite films increased gradually with the addition of cassava starch.Addition of cassava starch kept the pure films' little oil permeation rate.The WVTR of composite films decreased gradually with the addition of cassava starch in the range of 0-15% and it gradually increased when the cassava starch was more than 15%.The conclusion was: for the best properties of the composite films,the addition of cassava starch was better with no more than 15%.