p-CuO/n-In2O3 heterojunction nanofibers were prepared by solvothermal method using electrospun In2O3 nanofibers as template. The surface morphologies and microstructures of the composite nanofibers were characterized by field emission scanning electron microscopy(SEM), transmission electron microscopy (TEM), X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS). It was found that the In2O3 nanofibers were uniformly decorated with CuO nanoparticles, and the surface densities of CuO nanoparticles could be controlled by varing the precursor concentration of cupric acetate. Side. heated gas sensors were prepared based on these composite nanofiers. The p-CuO/n-In2O3 heterojunction nanofibers exhibited high gas responses and low operating temperature for detecting H2S gas compared with pure In2O3 nanofibers.