The paper presents the method of determining the sensitivity coefficient of flow stress with strain rate m (the strain rate sensitivity) during superplastic forming process of AA7075 aluminum alloy. The bulging free forming test was performed under constant gas pressures from 0.6 MPa and 0.8 MPa with temperatures of 5000C and 5300C. The values of the strain rate sensitivity varied from 0.3 to 0.6 with strain rate in the range of 5.10-4 to 1.5.10-3 (s-1), which can evaluate the superplastic forming ability of alloy in different technological modes. Tests results are allowed to choose the process parameters in the superplastic forming of AA7075 aluminum alloy sheet.