PVP/Sr1-xLaxFe12-xCoxO19(x=0-0.5) composite nanofiers were fabricated by Sol-Gel process and electrospinning technique. After high temperature calcination, Sr1-xLaxFe12-xCoxO19 (x=0-0.5) ferrite nanofibers were successfully obtained. The morphology, phases, structure and magnetic properties of the nanofibers were characterized by Scanning electron microscope(SEM), Transmission electron microscope(TEM), X-ray diffraction(XRD) and Vibrating sample magnetometer(VSM). The results show that the samples have an uniform diameter of 80-150 nm after calcined at 800 degrees C. The Sr1-xLaxFe12-xCoxO19(x=0-0.5) ferrite nanofiers all exhibit a hard magnetic performance, and chemical composition have considerable influence on magnetic properties of these ferrite nanofibers. The Sr1-xLaxFe12-xCoxO19 (x=0-0.5) ferrite nanofiers exhibit M-type strontium ferrites, CoFe2O4 phase and LaFeO3 phase at x >= 0.3. The substitutions of La3+ and Co2+ obviously increase the magnetic properties of the as-prepared samples at x <= 0.1, the coercivity(H-c), saturation magnetization(M-s) and remanent magnetization(M-r) of Sr0.9La0.1Fe11.9Co0.1O19 nanofibers are 432.02 kA/m, 54.7 A.m(2)/kg, 28.9 A.m(2)/kg, respectively. The magnetic properties of the fibers increase significantly, compared with that of the Sr0.9La0.1Fe11.9Co0.1O19 powder samples.