Effects of solution temperature, cooling method, holding time and sampling direction on the microstructure and mechanical properties of Ti17 alloy large size bar were studied in this paper, and the best heat treatment was selected according to the experimental results. The studies show that the strength of the alloy increases and the plasticity decreases with the increasing of solution treatment temperature. The strength of the alloy is higher and the plasticity is lower after solid solution treatment followed by air cooling and aging than that after solid solution treatment followed by water cooling and aging at the same temperature. The ductility of the alloy can be improved by shortening solution holding time under the same temperature and water cooling. The large size bar after being forged exists anisotropism.