PVA/[Gd(NO3)3+Yb(NO3)3+Er(NO3)3] composite nanofibers were fabricated by the combination of sol-gel method and electrospinning. Gd2O3:Yb3+, Er3+ upconversion nanofibers were obtained by calcination of the relevant composite nanofibers. The samples were characterized using XRD, SEM, TG-DTA, FTIR and fluorescence spectroscopy techniques. The results showed that the composite nanofibers were amorphous in structure, and Gd2O3:Yb3+,Er3+ upconversion nanofibers were cubic in structure with space group Ia3. The mean diameter of the composite nanofibers was ca. 140nm, and the Gd2O3:Yb3+,Er3+ upconversion nanofibers of 60nm in average diameter were acquired at 600°C. The water, organic compounds, nitrates in the composite nanofibers were decomposed and volatilized totally, and the weight of the sample kept constant when sintering temperature was above 600°C, and the total weight loss percentage was 81%. The FTIR spectrum of the composite nanofibers was basically the same as that of the pure PVA, and Gd2O3:Yb3+, Er3+ upconversion nanofibers were formed above 600ºC. Under the excitation of a 980 nm continuous wave diode laser, the Gd2O3:Yb3+, Er3+ nanofibres emitted strong green and red upconversion emissions centered at 522nm, 560nm and 659nm, respectively. The green emissions were attributed to the transitions of 2H11/2/4S3/2→4Il5/2 energy levels of Er3+ ions, and the red emission was assigned to the transition of 4F9/2→4Il5/2 energy levels of Er3+ ions. In the course of Gd2O3:Yb3+, Er3+ upconversion nanofibers formation, PVA acted as template. When the composite nanofibers were sintered, PVA was decomposed and evaporated, and rare earth nitrates were also decomposed and oxidized into Gd2O3:Yb3+, Er3+ nanoparticles, and these nanoparticles were mutually connected to form the Gd2O3:Yb3+, Er3+ upconversion nanofibers.