The invention discloses a treatment method for cobalt-nickel metallurgical wastewater slag. The treatment method is characterized in that coke is reduced for reducing metal such as zinc, manganese, cobalt, nickel, copper and iron in wastewater slag into elementary substances, calcium, magnesium, sodium and the like cannot be reduced into elementary substances, and washing is adopted for dissolvingcalcium, magnesium and sodium into hot water, so that calcium, magnesium and sodium are separated from other metals; zinc is separated from other metals through alkaline dissolving, properties of copper powder are relatively stable through acid dissolving, and copper powder does not react with acid, so that copper powder is obtained; and after iron of a solution for dissolving is removed througha sodium jarosite process, potassium permanganate is adopted for oxidizing manganese ions into manganese dioxide, and the rest of a cobalt-nickel solution is prepared into nickel-cobalt binary precipitates through homogeneous precipitation. The treatment method is short in flow, is simple in process, can realize separating and recycling of all components, is high in recovery rate; and the finallyobtained product is high in purity and is great in product additional value.