<p>Recycled acrylonitrile–butadiene–styrene (rABS) and recycled high impact polystyrene (rHIPS) are vital components of waste electrical and electronic equipment (WEEE) plastics, playing crucial roles in the recycling process. This paper utilized sodium chlorite (NaClO₂) to modify the surfaces of rABS and rHIPS, followed by flotation to separate the two types of plastics. X-ray photoelectron spectroscopy (XPS) test confirmed that the number of hydrophilic groups introduced on the rABS surface was more than that of rHIPS after surface modification. Through contact angle measurements, scanning electron microscope (SEM), and atomic force microscopy (AFM), it was confirmed that the modification on the rABS sample surface altered its microstructure and enhanced its surface wettability. The sodium chlorite concentration, modification temperature, and modification time significantly affected the floating percentage of rABS and rHIPS. The optimal surface modification conditions were determined to be a sodium chlorite concentration of 0.08&#xa0;mol L^-1, a modification temperature of 70&#xa0;°C, and a modification time of 60&#xa0;min. Under these conditions, efficient separation of rABS and rHIPS was achieved, with floating percentage of 3.62 and 96.39%, respectively. Therefore, surface modification using sodium chlorite can be utilized to facilitate the flotation separation of rABS and rHIPS.</p>