In this paper, the effects of electrospun polysulfone/ CNTs hybrid nanofibers on mechanical properties of epoxy resin were investigated. The CNTs functionalized with the mixture of H2SO4 and HNO3 were characterized through Fourier transform infra-red spectroscopy (FTIR), and the morphorgy of functional CNTs was observed by transmission electron microscopy (TEM). The PSF/CNTs solutions with 1 wt %, 5 wt %, 10 wt % CNTs content were electrospun to fabricate hybrid nanofibers. The morphologies of PSF/CNTs nanofibers were observed by scanning electron microscopy (SEM) and TEM. Experimental results showed that the diameters of the nanofibers were reduced with increasing CNTs contents, and the CNTs were embedded dispersally into the nanofibers. The 2 wt % PSF/CNTs hybrid nanofibers toughened and reinforced epoxy with different CNTs contents were prepared, and compared the mechanical and thermal properties to those of PSF nanofibers toughened epoxy and pure resin matrix. The tensile strength of toughened and reinforced epoxy were higher than those of epoxy resin toughened with the same content of PSF nanofibers. Dynamic mechanical thermal analysis (DMTA) showed the glass transition temperature (Tg) of PSF/CNTs nanofibers toughened and reinforced epoxy increased by 10°C compared to that of epoxy matrix. SEM observations of toughened and reinforced epoxy showed that PSF spheres resulting from the inhomogeneous phase separation were aligned in random orientation and CNTs at different sites were dispersed in epoxy matrix or PSF spheres.