Abstract: In order to solve the problems that arise from industrial draining water taking Co2+, we have investigated and examined the contributing factors to the adsorption efficiency, including the amount of the fly ash to be added to the Co2+-containing solution, pH, the stirring speed, the adsorption time and temperature during the adsorption treatment. It is shown that the adsorption effect of fly ash to Co2+ is surprisingly good. On most occasions in our survey, the Co2+ in the micro liquid waste can be totally adsorbed by certain amount of fly ash under appropriate conditions. With other contributing factors fixed, the adsorption efficiency proves to increase not only with the increase in the stirring speed and the amount of ash added, but also with the decrease of the absorption temperature. In conclusion, the adsorption efficiency can be made desirable by using fly ash under ideal conditions.