Abstract:“Chemical precipitation in the mild alkaline solution” was usually adopted to treat environmental cadmium pollution emergencies in rivers. After the emergency response, whether cadmium flocs in the bottom of the river release cadmium drew the attention of people. The effects of pH, rotating speed, the sediment content, and the temperature on the cadmium release were estimated in this study. The experimental results showed that the effect of pH was appreciable. The cadmium concentration was increased at the lower pH, and it decreased with pH increase. The cadmium concentration was 1.36 times than that in the standard of 5 μg/L at pH 5, and it didn’t exceeded the standard within pH 6~9. The increase of sediment decreased the concentration of cadmium because sediment were the kind of coagulant. The cadmium concentration was 0.24 times than that in the standard under the condition of 360r/min, pHo5, and sediment content of 0.03 g/L. Cadmium ion concentration decreased with the increase of rotating speed. The cadmium flocs remained stable when the temperature ranged from 10 to 20, and the cadmium concentration decreased with the time at 30℃.