Abstract: On the basis of the preparation process of soybean isolated protein film, composite film of modified cellulose and soybean isolated protein was prepared by adding original cellulose, carboxy methylated cellulose (CMC) and hydroxy propyl methyl cellulose (HPMC) . The effects of the seven performance indicators on composite film by different dosages of three added materials, which were film thickness (FT) , film integrity (FI) , tensile strength (TS) , E (Elongation at Break) , T (Transmittance) , D (Dissolution Ratio) and WVP (Water Vapor Permeability) , were inspected. The scanning electron microscopy (SEM) graph of the soybean isolated protein (SPI) film and the composite film adding respectively the three kinds of material were analyzed. The best adding material was chosen and the optimum adding amount was studied. The results showed that:when the mass percentage of the HPMC and soybean isolated protein was 4%, the tensile strength of composite film reached the maximum of 4.43MPa, and the water vapor permeability reached the minimum of 21.0g·mm/ (m2·h·kPa) , and the elongation at break and transmittance rate were relatively ideal.