In this study, polystyrene-b-poly (ethylene/propylene)-b-polystyrene grafted glycidyl methacrylate (SEPS-g-GMA) copolymer was prepared by melt grafting in the mixer. The successful grafting of GMA on the SEPS molecular chain was analyzed by Fourier transform infrared spectroscopy (ET-IR). The grafting ratio of SEPS-g-GMA was measured by acid-base titration, which showed that N-vinylpyrrolidone (NVP) had a positive effect on the increased grafting ratio of SEPS-g-GMA. The recycled polypropylene (R-PP)/ recycled high impact polystyrene (R-HIPS) blends were prepared by a melt extrusion, and the effect of SEPS-g-GMA copolymer with different ratios on the compatibility of blends was studied. The epoxy groups in SEPS-g-GMA copolymer were found to have a chemical reaction with the carboxyl groups in the waste materials. When the grafting ratio of SEPS-g-GMA was 2.44%, the notched impact strength and the elongation at break of the R-PP/R-HIPS blends with lOphr SEPS-g-GMA reached 7.06 kj/m(2) and 34.25%, which were significantly increased by 186.99% and 68.30% compared with that of pure blends, respectively. Moreover, the observed decreased particle size and increased dispersion uniformity improved the compatibility using SEPS-g-GMA. The increased complex viscosity, storage modulus and loss modulus indicated that the chemical reaction between SEPS-g-GMA and R-PP/R-HIPS blends improved the component compatibility among the blends, resulting in the chain entanglement prominently. The presence of SEPS-g-GMA inhibited the degradation and increased the thermal stability of RPP/R-HIPS blends. (C) 2018 Elsevier Ltd. All rights reserved.