Abstract: In order to solve the problem of environmental pollution caused by straw burning and plastic film, straw resources should be utilized with high value. The method of the central composite rotatable quadratic orthogonal experimental design was applied to explore the possibility for preparing soybean straw fiber as clean, high strength and high yield raw material for biodegradable film with physical method. The effects of material characteristics and operating parameters on soybean straw fiber properties and optimal parameters combination were studied. Soybean stalk length, soak time, operation temperature, spindle speed and feeding rate were selected as influence factors. Fiber yield, fiber aspect ratio and tensile strength were selected as response functions. The Design-expert 6.0.10 software was applied to design the scheme and analyze the data. The results showed that 1) with the parameters of straw length 7 cm, soaking time 24 h, feeding rate 27 g/min, operation temperature 80~85℃ and spindle speed 110~120 r/min, the fiber yield was over 80%, dry tensile strength was over 7 N, aspect ratio was over 5. 2) The order of contribution rate of all the factors on fiber yield was: soak time>spindle speed>feed rate>stalk length> operation temperature; The order of contribution rate of all the factors on tensile strength was: stalk length> operation temperature> feed rate>soak time>spindle speed; The order of contribution rate of all the factors on fiber aspect ratio was: feeding rate>stalk length>operation temperature>soak time>spindle speed. The research can provide a theoretical and technical support for manufacturing biodegradable film with soybean straw.