Dilatometry method was used to study the omega phase transformation kinetics of a near-beta titanium alloy Ti-7Mo-3Cr-3Nb-3Al during continuous heating. The local activation energy as a function of transformed volume fraction f (omega) was determined by Kissinger-Akahira-Sunose (KAS) method, which increases with the transformation proceeding and the average value is about 85.06 kJ/mol. The nucleation and growth mechanism of the omega phase was investigated by the non-isothermal local Avrami exponent n, which appears a significant change with the transformed volume fraction, indicating that the transformation mechanism varies at different stages. The local Avrami exponent lies between 0.5 and 2 in a wide transformed volume fraction range of 0.05-0.9, indicating that the dominating mechanism of omega phase transformation in Ti-7333 titanium alloy is the three-dimensional growth with a near-zero nucleation rate.