In this work, the mesoporous SiO2 nanofibers from pyrolyzing precursor of electrospun nanofibers were employed as support to immobilize PtNi nanocatalyst (PtNi/SiO2 nanofibers). AFM, XRD, SEM, TEM, XPS, ICP-AES and N-2 adsorption/desorption analysis were applied to systematically investigate the morphology and microstructure of as-prepared products. Results showed that PtNi alloy nanoparticles with average diameter of 18.7 nm were formed and could be homogeneously supported on the surface of porous SiO2 nanofiber, which further indicated that the SiO2 nanofibers with well-developed porous structure, large specific surface area, and roughened surface was a benefit for the support of PtNi alloy nanoparticles. The PtNi/SiO2 nanofibers catalyst exhibited an excellent catalytic activity towards the reduction of p-nitrophenol, and the catalyst's kinetic parameter (k(n) = 434 x 10(-3) mmol s(-1) g(-1)) was much higher than those of Ni/SiO2 nanofibers (18 x 10(-3) mmol s(-1) g(-1)), Pt/SiO2 nanofibers (55 x 10(-3) mmol s(-1) g(-1)) and previous reported PtNi catalysts. The catalyst could be easily recycled from heterogeneous reaction system based on its good magnetic properties (the Ms value of 11.48 emu g(-1)). In addition, PtNi/SiO2 nanofibers also showed an excellent stability and the conversion rate of p-nitrophenol still could maintain 94.2% after the eighth using cycle.