The invention relates to a method for separating ABS and PS from waste mixed plastics. The method comprises the following steps of the step 1 of preprocessing the waste mixed plastics, after washing and drying of the waste mixed plastics, crushing the waste mixed plastics into plastic mixed powders, and the fineness of the plastic mixed powders is smaller than 10 microns; the step 2 of carrying out magnetic separation and gravity separation, putting the plastic mixed powders into a magnetic separator to remove magnetic metal substances in the waste mixed plastics, then carrying out the gravityseparation to leave grouped substances with lighter weight for later use, carrying out the secondary gravity separation on the grouped substances to separate polyolefin plastic and styrene plastic from the grouped substances; the step 3 of dissolving, putting styrene plastic mixed powder obtained in the step 2 into an organic solvent to obtain a filtered substance and a dissolved solution throughfiltering, wherein the organic solvent comprises 75-80% of acetone and 15-20% of n-ethane; and the step 4 of extracting a solute from the dissolved solution obtained in the step 3 to obtain the ABS,carrying out vibration filtration on the filtered substance to obtain a swelling substance and an insoluble substance, and carrying out flash evaporation on the swelling substance to obtain the PS.