Microstructure evolution of Ti14 (α＋Ti2Cu) alloy during isothermal process at different semi-solid temperatures was researched. It is found that both the semi-solid temperature and holding time would affect the morphology of grain boundary and the grain size. The grains grow obviously and the grain’s shape becomes globular with increasing the holding time, the distribution of liquid on grain boundary changes from discontinuous to continuous to form a latticed structure finally. According to the statistic analysis of experimental data, the grain growth index is 0.88 and 0.97 at 1000 ℃ and 1050 ℃, respectively, indicating that the rising of isothermal temperature would accelerated the microstructure evolution