Adding large-diameter hyperelastic NiTi shape memory alloy (NiTi-SMA) bars to damping elements can achieve good self centering ability. However, due to the high sensitivity of SMA materials to temperature, different heat treatment processes can have a certain impact on the mechanical properties of NiTi-SMA bars, resulting in varying degrees of influence on the energy dissipation and self centering ability of dampers or supports containing NiTi-SMA bars. Therefore, it is necessary to explore the effects of different heat treatment processes on the mechanical properties of large-diameter NiTi-SMA bars. This article first conducted different heat treatment processes on 7 Ni-59.9% atTi bars with a working section diameter of 9mm, followed by amplification cyclic tensile tests to investigate the effects of different heat treatment processes and amplification cyclic tensile tests on the stress-strain relationship, residual strain, energy dissipation capacity, and other properties of the specimens. The research results indicate that appropriate heat treatment can significantly improve the superelasticity of NiTi-SMA bars, with a typical flag shaped stress-strain curve. The optimal heat treatment temperature and duration for NiTi-SMA bars with a working diameter of 9mm are 400 ° C and 30min, respectively; The closer to the optimal heat treatment process, the more stable the energy dissipation capacity, secant stiffness, and equivalent damping ratio of the specimen become.