MWNTs-EP were successfully prepared by functionalization of MWNTs with epoxy-based groups, and MWNTs-EP/polysulfone (PSF) hybrid nanofibers were fabricated to obtain ex-situ dispersion and alignment of MWNTs-EP by electrospinning. The prescribed morphology and interface correlation of hybrid nanofibers reinforced and toughened epoxy matrix (RTEP) were investigated. The alignment degree of hybrid nanofibers was enhanced with increasing MWNTs-EP loadings, and MWNTs-EP were found to be well dispersed and aligned along the nanofiber axis. The dispersion and alignment states of MWNTs-EP during inhomogeneous phase separation of RTEP were proposed and verified. MWNTs-EP dispersed and aligned along the orginal nanofiber axis were enveloped, bridged or pinned by PSF spheres arranged in the nanofiber direction. The interface chemical correlation between MWNTs-EP and resin matrix was generated due to the further reaction of epoxide rings on the surface of MWNTs-EP, which resulted in simultaneous improvement of mechanical and thermal properties of RTEP. (c) 2012 Elsevier Ltd. All rights reserved.