With the Superplastic forming technology, the problem that the forming of the complex titanium alloy parts is difficult has been solved. The high temperature forming characteristics of the titanium alloy material and the establishment of the constitutive model of material that will be used as the material model of the simulation of the material forming (the minimum thickness is larger than 0.8 mm) about the negative Angle parts are based on high-temperature tensile test. The influence of the thickness of the parts is analyzed from three different SPF schemes, which are simulated by the MSC.MARC software. The results demonstrate the parts taking advantage of two-stage SPF, which is consisted of concave die SPF method and convex die SPF method can meet the requirement of minimum thickness and improve the thickness distribution on the die draft sides. Furthermore, the thickness distribution of the parts is more uniform with the convex die SPF method.