A dual-layer dielectric film of Ge/GeO2 hollow-core mid-infrared fiber was proposed. The capillaries with single circle air holes are made by stack-draw method, which are then covered by a layer of silica gel in the following procedure to increase the mechanical strength of the structure. The dual-layer dielectric reflection films of GeO2-Ge on inner wall of the quartz capillary were deposited by CVD and hydrogen reduction. The reflection efficiency at the short wave band is raised in this way. From the spectrum analysis, the fiber transmission wavelength spreads from 3 to 12 μm without apparent absorption.