ABSTRACTAlthough polysulfone (PSU) is a potential thermoplastic engineering plastic with high heat resistance, good dimensional stability and excellent mechanical properties, its poor processability has greatly restricted its application in electrical, aerospace, and medical fields. In this work, polyamide 6 (PA6) and PSU‐PA6 block copolymer (PSU‐b‐PA6) were used to improve the processibility and formability of PSU depending on their excellent fluidity and good compatibility between two components. Furthermore, the fluidity, thermal and mechanical properties of the blends were carefully investigated. It was found that, melt flow index of PSU could be increased above 10 times, and strength and toughness could be enhanced by 4–10% with the introduction of 10 wt % PA6 and PSU‐b‐PA6 without compromising the heat resistance of PSU obviously. The processing conditions of PSU could be improved while maintaining a decent comprehensive performance. Thus, the method has great potential for extending the applications of PSU. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41139.