Abstract: In the process of sweet potato starch production, a large amount of starch processing water is produced, which contains a lot of protein. The protein extraction from sweet potato starch processing water by acid-heat flocculation was studied. Through the single factor experiment, pH, temperature, centrifugation time and centrifugation speed were selected as variables. The main factors and optimum conditions were studied through orthogonal experiments. While, the effect and technical and economic feasibility of extracting protein from sweet potato starch processing water were analyzed through process simulation test with an integrated device. The results showed that the removal rates of TN and COD_Cr of sweet potato starch processing water reached 76.79% and 40.66%, respectively, when the temperature was 100 ℃, pH was 4.0, the centrifugation speed was 3 500 r/min and the centrifugation time was 10 min. The process simulation test results of the integrated device showed that the sweet protein recovery rate reached 48.86%, and the protein content (dry basis) of the recovered crude protein powder was 73.22%, which met the requirements of animal feed raw materials. In addition, for a medium-sized or large-sized sweet potato starch enterprise, 1 m³ sweet potato starch processing water could create a gross profit of 20.51 yuan by recycling protein. The protein extraction from sweet potato starch processing water by acid-heat flocculation had both technical and economic feasibility, which had a good promotion prospect.