The Nb/SnO2 composite thin films were successfully synthesized by sol-gel spin-coating method on glass substrate. The structures and properties of Nb/SnO2 composite thin films were characterized by X-ray diffraction (XRD), scanning electron microscopey (SEM), ultraviolet visible near-infrared spectrophotometry and four-probe method. The effects of Nb doping on structure and optical-electrical properties of the Nb/SnO2 composite thin films were researched. The results indicate that a tetragonal rutile structure is retained when the Nb content is less than 0.99at%, and the nano-particles are distributed homogeneously in the thin films and their size can be controlled in the range of 5—7 nm. The resistivity of Nb/SnO2 composite thin films decreases and then increases when the Nb content is less than 0.99at%, and reaches a very low value of 9.49×10-2 Ω ·cm at 0.37at% Nb. In the range of 400—700 nm visible region, the transmittance of Nb/SnO2 composite thin films is up to 90% when the Nb content is less than 0.99at%, and the optical band gap of Nb/SnO2 composite thin films are in the range of 3.9—4.1 eV. The visible light transmittance of Nb/SnO2 composite thin films significantly reduce at 1.23at% Nb.