The invention relates to a tailing wastewater treatment process after mineral dressing production of nonferrous metals, and discloses a method for reducing content of cupric ions in waste water discharged from a tailings pond. A tailings disposal process comprises processes of tailings concentrating and dewatering, fine grained tailings reconcentrating, and tailings sand precipitating, and further comprises the step of adding a polymeric aluminium oxide reagent for adsorbing the cupric ions, and the tailings concentrating and dewatering step is that tailings slurry discharged from a dressing plant is delivered to a dehydration bucket for dehydration treatment, so that heavier coarse grained tailings is settled to the bottom of the dehydration bucket and forms coarse grained sand setting, the lighter fine grained tailings overflows with pulp from the upper layer of the dehydration bucket to form fine-sized tailings pulp; after dehydration treatment is completed, the coarse grained sand setting directly enters in a tailings sand setting process, and the fine-sized tailings pulp is mixing with the polymeric aluminium oxide reagent, then enters in a reconcentrating process. A method for reducing content of the cupric ions in the waste water discharged from the tailings pond has the characteristics that the cost is low, the operation is simple, and the environmental compliance is realized.