In this paper, we report on the annealing temperature dependence of the upconversion (UC) phosphor of TiO2-ZnO doped with Yb3+ and Tm3+. We prepared samples using metal-organic decomposition (MOD) solutions and Tm2O3 powder, which were analyzed in terms of their photoluminescence (PL) spectra and crystal structures. The PL spectra showed a blue UC phosphor band at a wavelength of 476 nm. The emission intensity was greatest after annealing at 850 degrees C. By analyzing the crystal structures using an X-ray diffractometer (XRD), it was found that there was a large amount of RE2Ti2O7 in the samples annealed at 900 degrees C and above.