The major advantage of superplastic forming (SPF) technology is that it can form integral and complex components in simple operation, since it is possible to form one or more sheets of superplastic grade metal into single surface tools by relatively low gas pressure. Duplex steel contains two phases in nearly equal proportions which can suppress grain growth at a high temperature, like superplastic Ti-6Al-4V, and many duplex stainless steels with fine grained microstructures show superplastic behavior. In this study, superplastic forming technology was developed to fabricate a duplex stainless steel sheet for the outer surface of liquid propellant combustion chamber. Superplasticity of this alloy was investigated and forming methodology was analyzed and developed. The experimental results show a complex configuration of aerospace component was successfully fabricated by superpalstic forming of a sheet of duplex stainless steel.