Gallium and titanium co-doped zinc oxide (GZO:Ti) thin films were dep osited on glass substrates by radio-frequency (RF) magnetron sputtering.The effect of depositing temperature on microstructure and optical properties of the thin films is investigated.The crystal structure and transmi ttance spectrum of the thin films are characterized by X-ray diffraction and UV-visible spectrophotometer,resp ectively.The optical constants of the thin films are obtained by spectrum fitting method.The results indicate th at all the deposited thin films possess hexagonal wurtzite structure with a strong growth orientation along the (002) c-axis.The deposition temperature plays an obviously regulative role on the microstructural parameters ,optical constants and optical band gap.The film deposited at temperature of 653K exhibits the largest crystallite size of 82.12nm,the lowest dislocation density of 1.48×10－4 nm－2,the lowest micro-strain of 0.0014,the highest average visible transmittance of 82.06% and the maximum optical band gap of 3.57eV.