Near–isothermal forging experiments of the TG6 titanium alloy have been conducted at the deformation temperatures ranging from 850 to 1075 ℃with a constant strain rate and deformation degree. The primary α phase content in the alloy after solution, deformation and heat treatment, and the thickness of lamellar α phase in the alloy after heat treatment were measured by OM and image analyzer. The results show that compared to solution state, both forging and forging + heat treatment cause the decrease or increase of primary α phase content when forging temperatures are below or over 1000 ℃. The thickness of the lamellar α phase increases with the increase of forging temperature, which is caused by the decrease of nucleation density of secondary α phase. The β phase grains are so big when the forging temperature is 1075 ℃, while their microstructures are non–uniform. The room temperature and 600℃ tensile properties, impact property and fracture toughness of TG6 alloy have also been measured. It is found that the tensile strength of the TG6 alloy is not very sensitive to forging temperature. The plasticity decreases but the fracture toughness increases with the increase of forging temperature. There is no obvious change in the impact toughness when forging in the α and β double phase field, however it decreases when forging temperature is near the β transformation temperature. The change in mechanical property was explained by SEM, TEM and OM experiments.