The high temperature Raman spectrum of LiTaO3 was studied from 298 to 948 K by micro-confocal Raman technique and the mechanism of phase transition from ferroelectric phase to paraelectric phase was studied by analyzing the high wave number Raman peaks of LiTaO3. The experimental results show that all the Raman peaks except 466.7 cm-1 have a remarkable Raman shift to low frequency when increasing temperature. The full width at half maximum (FWHM) of all Raman peaks increases with increasing temperature, but the intensity weakens. At about 933 K, the phase transition is observed since the three Raman peaks disappear. And at about this temperature, the FWHM of 359.5, 385.0 and 466.7 cm-1 shows an obviously superlinear increasing. From the experimental results, we conclude that the phase transition is a mixed phase transition, and the phase transition is reversible.