The invention discloses a reagent recovery system and method for nickel-tin salt coloring and medium-temperature hole sealing in aluminum processing. The system sequentially comprises a nickel-tin-containing wastewater intercepting unit, a nickel-tin-containing wastewater collecting unit, a tin ion recovery unit and a nickel ion recovery unit from the upstream to the downstream; and the nickel-tin-containing wastewater intercepting unit comprises a 13# nickel-tin salt coloring tank, a 14# flowing water-washing tank, a 15# high-pressure atomization spraying tank, a 16# medium-temperature hole sealing tank, a 17# flowing water-washing tank and an 18# flowing water-washing tank which are sequentially arranged. The system and the method are used for the toxic nickel-tin-containing waste residue generated in oxidation coloring and hole sealing in aluminum processing, an online classification recycling and compatible method is utilized, the reagent component is finely selected, the system isskillfully configured, the recycled nickel-tin-containing product is recycled to the 13# nickel-tin salt coloring tank, so that the resource recycling of the toxic-containing waste is realized; and about 1600 million tons of nickel-tin-containing wastewater generated in oxidation coloring and hole sealing in aluminum processing can be treated on line, about 4 million tons of the toxic nickel-tin-containing waste residue is converted, and about 10 million tons of the nickel-tin salt coloring agent are generated.