The high-temperature tensile experiments were conducted to study the stress relaxation behavior of Hastelloy C-276 Alloy at various temperatures and initial stresses. As a result, a set of stress relaxation curves of Hastelloy C-276 Alloy were obtained and these curves can be fitted by twice delay function well. The relationships between creep strain rate and stress were derived from the experimental stress relaxation curves. In addition, the effects of temperature on the stress relaxation behavior of Hastelloy C-276 Alloy were also discussed. This work lays a theoretical foundation for numerical simulation of vacuum hot bulge forming process of rotor-can