Abstract: The major components of cassava starch maize plasm wastewater were analyzed to understand the subsequent processing and recycling of cassava starch wastewater. Isoelectric points of protein in the maize plasm cassava starch wastewater were between 3.5 to 4.5. Through the single factor experiment, pH, precipitation time, temperature and concentration of protein in cassava yellow pulp wastewater were selected as variables. The acid precipitation technology of protein in cassava starch maize plasm wastewater was studied by the orthogonal test. The results showed that the precipitation rate of protein were obtained reach as high as 98.3%, when the initial pH was 4.0, the temperature was 35℃, the precipitation time was 3.0h, and protein concentration for 1400mg/L. Cassava starch wastewater precipitated protein contained 15 kinds of amino acids, it could be used as animal feed additive.