Abstract: Rice husk resources are rich in China, which, after complete combustion, can produce byproducts containing about 90% silicon. It would cause a great waste of resources as well as environmental pollution if they were not timely utilized. In order to enhance the added value of the byproducts of foods and protect the environment, this study prepared high-purity white carbon black by dissolving SiO₂ out of rice husk ash with the method of alkali dissolution and acid precipitation. This study first investigated the effects of liquid-solid ratio (sodium hydroxide solution/rice husk ash), reaction temperature, and the pH value of reaction endpoint on the purity of white carbon black via single-factor test. Then, the preparation process of white carbon black was optimized by Box-Behnken center combination experimental design. The results showed that factors affecting the purity of the white carbon black were in this order: reaction temperature > the pH value of reaction endpoint > liquid-solid ratio. The influence of the temperature of reaction endpoint on the purity of white carbon black was extremely significant, and the interaction between the pH value of reaction endpoint and the liquid-solid ratio was also significant. The optimum preparation conditions were as follows: the ratio of sodium hydroxide solution to husk ash was 11 (mL/g), the reaction temperature was 60 ℃, the pH value of reaction endpoint was 10. Under these conditions, the purity of white carbon black can be maximized up to 98.56%, and it was under national standards characterized by infrared spectroscopy.