Tin dioxide (SnO₂) is a wide band gap semiconductor. SnO₂ has recently received a large interest because of its multiple technological applications, including solar cells, optoelectronic devices, flat panel displays, gas sensors, architectural windows and catalysts, owing to its good optical and electrical properties and excellent chemical and thermal stability. Compared to traditional materials which based on sulfur compound, rare earth elements doped oxides possess obvious advantages, such as good chemical stability, high transparency in the range of visible light, and nontoxic. In this work, the Ce-Cu codoping of SnO₂ thin films were prepared by sol-gel method. The influence of Ce-Cu codoping on the microstructural and optoelectrical properties has been investigated. Both Cu and Ce dopants are incorporated at substitutional sites (C{u}_{Sn}^{2+}, C{e}_{Sn}^{3+}), acting as the acceptors. With increasing the Ce content, the film grain size and optical band gap decrease, while the resistivity decreases at first and then increases due to the change of spatial trap distribution. The ultraviolet peak of the films can be attributed to the oxygen vacancies, while the blue emission at 470 nm belongs to the electron transition between 5d excited state and 4f state of Ce³⁺ ion. Besides, the intensity of the visible emission peak is influenced by the Ce content. The band structure, density of states of SnO₂, intrinsic and doped separately with Cu and Ce were investigated by first-principles full potential linearized augmented plane wave method. The Ce-Cu co-dopants make the conduction band shift down and induce a fully occupied impurity band above the valance band, and 4f orbital of Ce inserts into the conduction band, which leads the shift of the bottom of the conduction band to lower energy zone and narrowing of band gap, thus the band gap is decreased and the conductivity is improved.