The high-temperature tetragonal structure of Ta2O5 was observed in a Ta2O5 ceramic sample doped with 8 at.% TiO2. Direct evidences for the modulation along [(1) over bar 10] direction caused by Ti replacing Ta are obtained based on atomic-resolution high-angle annular dark-field lattice imaging and electron energy loss spectroscopy analysis. The atomic mechanism of Ti substitution of Ta is explicitly described based on the structure model along [110] direction projection.