Polysaccharides are often used as food degradable packaging materials. Chitosan and cellulose nanofibers as edible film substrates have good waterproof performance， but lack of mechanical properties and physical and chemical properties. In this experiment， different concentrations(0%， 0.5%， 1%， 1.5%， 2%) of soybean protein isolate (SPI) were mixed with chitosan and cellulose nanofibers to prepare edible membranes. Fourier transform infrared spectroscopy (FTIR)， X-ray diffraction (XRD)， differential scanning calorimetry (DSC)， scanning electron microscopy (SEM) and other methods were used to study the microstructure， electrostatic action and the influence on the properties of edible films. The results show that the interaction between SPI and chitosan and cellulose nanofibers is mainly hydrogen bond and electrostatic， and the interaction is the strongest when the SPI content is 1%. The network structure is dense and the cross section becomes smoother. When SPI content is 1%， the tensile strength and elongation at break of edible membrane are significantly increased to 6.42 MPa and 97.47%， the opacity and contact angle are significantly increased， the water vapor transmittance and oxygen transmittance are decreased to 0.86 g·mm·m-2·h-1·kPa-1 and 10.63 g·m-2·d-1， respectively. Water absorption and solubility are obviously weakened. The above analysis shows that adding 1% SPI can optimize the performance of the edible membrane. This experiment provides theoretical reference for the preparation and application of the proteoglycan edible membrane.