This paper studies the influence of the strain rate during the superplastic forming on the microstructure evolution of Ti-4Al-3Mo-1V titanium alloy. The finite elements simulation (FES) of the superplastic forming process at a temperature of 875 °C, which considered to be the optimum forming temperature of this alloy, and at a constant uniform gas pressure of 0.4, 0.7, and 1 MPa were performed. The strain rate response across the formed part via FES at each applied gas pressure was analyzed. The superplastic forming using the same forming condition of the FES, applied gas pressure and forming time, was performed via lab forming machine. In initial state before forming, the studied alloy exhibits a mixture of lamellar and equiaxed grain structure. The microstructure evolution after the superplastic forming process for each applied gas pressure was investigated. It was observed that the lamellar microstructure significantly affects the superplastic forming process and the uniformity of the thickness profile after forming.