High refractive index TiO2 thin films were deposited on BK7 glass by reactive electron - beam(REB) evaporation at pressure of 2 × 10- 2 Pa, deposition rate of 0.2nm/s and at various substrate temperaturesfrom 120℃ to 300℃ . The refractive index and the thickness of the films were measured by visible spectroscopic el-lipsometry (SE) and determined from transmission spectra. Optical properties and structure features were charac-terized by UV - VIS, SEM and XRD, respectively. The measurement and analysis on transmission spectra of allsamples shaw that with the substrate temperature increasing from 120℃ to 300℃ , the refractive indices of thinfilms increase from 1.7 to 2.1 and the films after heat treatment have higher refractive indices due to its crystalliz-ing. The XRD analysis results indicate that the structure of TiO2 thin films deposited on BK7 glass at substratetemperatures of 120℃ ,200℃ and 300℃ is amorphous, after post-annealing under air condition at 400℃ for 1hour, the amorphous structure is crystallized, the crystal phase is of 100% anatase with strong preferred orientation(004) and the grain size of crystalline is within 3.6-8.1 nm, which is consistent with results from SEM observation.