ITO:Nb thin films with the thickness of 300 nm were prepared by magnetron sputtering using a ceramic niobium doped ITO target at the temperature from room temperature to 300 °C. The structure, conductivity, and the optical transmission in the visible region of ITO:Nb films were investigated. The results of XRD analysis indicate that ITO:Nb thin films are In2O3 single phase. AFM images show that the surface roughness of the film increases with the temperature increasing. The resistivity decreases as the temperature increasing, reaching a minimum value of 1.2×10-4 Ω·cm at 300 °C due to the rising of both Hall mobility and carrier concentration. The average transmittance of films in the visible light region is over 87%. The optical band gap becomes wider and red shift of the absorption edge takes place with the rising of the temperature, which is coincident with the variation trend of the carrier concentration