Abstract: Abstract: Nano-crystalline cellulose (NCC), chitosan (CS) and soy protein isolate (SPI) are all economic renewable products. Due to their degradability, high safety and special nutritious and healthcare function, they are ideal raw materials to prepare edible membranes. NCC boasts the advantages of high crystallinity, high strength, high specific surface area, environmental-friendliness and low cost. Their molecular structure contains a large amount of -OH. When mixed with the other natural macromolecules, they might easily form intermolecular and intramolecular hydrogen bonds to contribute to the stability of the structure of blended materials. The NCC adopted by the paper comes from the sunflower seeds hull, a kind of industrial production waste. The CS boasts favorable biocompatibility and biodegradability. Edible membranes with CS as the basic material can effectively prevent the occurrence of food pollution and corrosion, and extend the expiration date of food. SPI is a kind of vegetable protein with rich sources and nutrition and prepared through alkali dissolution acid sedimentation, whose protein content can reach above 90%. Soybean β-conglycinin, 7S, glycinin, and 11S, are its major components. As a highly nutritious plant protein, SPI has a lot of hydrogen bonds, ionic bonds and hydrophobic bonds in its molecular structure, so it has a favorable membrane-forming property. Despite of a strong performance of air resistance, SPI is poor in terms of its mechanical strength. Although there is poor performance for the single membrane-forming component existing in practical applications, the performance of edible membrane can be improved by adding one or multiple natural materials with SPI as the basic membrane-forming material. In order to study edible membrane with a favorable performance and its preparation methods, this paper adopts SPI as the basic membrane-forming material, and adds NCC and CS into the material. The edible membrane is prepared through the alloying-casting-evaporation method. The single-factor experiment is conducted to study the influence of the material ratio, the pH value of membrane-forming materials and the mass concentration of edible membrane on the tensile strength, elongation at break, water vapor permeability and oxygen permeability of edible membrane. The principal component analysis (PCA) and the membership comprehensive rating are combined to work out the comprehensive score of the performance of edible membrane. In the single-factor experiment, the comprehensive score of edible membrane performance is adopted as the response value and various factors as independent variables. The response surface method is employed to optimize the process parameters. The quadratic polynomial mathematic model is built, and the validity of the model and the interaction between various factors are analyzed. Through the analysis of the model, the influence degree of various factors on edible membrane is in the following order: pH value ＞ membrane-forming material ratio ＞ mass concentration of glycerol. The optimal processing conditions for edible membrane are: membrane-forming material ratio is NCC:CS:SPI of 1.25:0.75:2, pH value is 3.59, and mass concentration of glycerol is 0.02 g/mL. Under the optimal conditions, the comprehensive score of the performance of edible membrane is predicted to reach 0.63. Through the verification experiment, the comprehensive rating of the performance of edible membrane is 0.62, the tensile strength was 19.56 MPa, elongation at break was 18.20%，water vapor permeability was 0.73×10-13 g/(cm·s·Pa) and oxygen permeability was 2.21×10-5 cm3/(m2·d·Pa) of edible films. This suggests that the process optimization is scientifically viable, and the infrared and scanning electron microscopic results suggest there is a good compatibility between membrane materials. The research findings of this paper can provide references for production and applications of edible membrane.