Abstract: The process of superplastic forming(SPF)and diffusion bonding(DB)for two-sheet structure of Ti-6Al-4V titanium alloy was performed.The SPF and DB process was simulated by using finite element software Marc to optimize the curve of pressure-time and predict the thickness and shape of formed part.Then the calculated results were compared with the test results which were obtained using thermal forming machine.The results show that the optimum parameters for the SPF process were: forming temperature of 900 ℃,forming pressure of 2.5 MPa and forming time of 1 000 s.The thickness of surrounding region for the sheet was the thinnest while the middle region was the thickest and the thickness distribution of the upper panel was more uniform than that of the lower panel during the superplastic forming.The thickness distribution of the formed part was in good agreement with the predicted results.While the optimum parameters for the DB process were bonding temperature of 900 ℃,bonding pressure of 3 MPa and bonding time of 80 min.The bonding ratio at the interfaces was excellent.