The work aims to study the influence of various factors (liquid ratio (the ratio of mass of oven dry material to that of the water), cooking temperature, holding time and sodium hydroxide) on the preparation process of rice straw fiber, and the feasibility of producing functional molded packaging materials with rice straw fiber. The single factor method was used to study the influence of various factors on the straw fiber separation process. The straw fibers were analyzed by the test of mechanical properties and electron microscope scanning. The optimum straw fiber preparation process was determined. The liquid ratio was 1︰5, the cooking temperature was 100 ℃, the holding time was 90 min and the amount of NaOH was 8% (the amount indicated the ratio of such drug to the mass of the oven dry material of the rice straw). The coarse pulp yield of the process was 73.97%, the fracture length was 6254.05 m, the bending strength was 76.13 MPa and the elastic modulus was 6813.71 MPa. From the SEM images, it could be seen that the fibers bound more closely after alkali treatment. The alkali-treated straw fiberboard has compact structure and greatly improved mechanical properties, and it can replace the paperboard prepared from waste paper. In the treatment process, the NaOH amount and the cooking temperature have a great influence on the material properties, and the carbohydrate degradation in the slurry should be avoided as much as possible.