Abstract: The Spectrometer Ring (SRing), which is an important component of the High Intensity heavy-ion Accelerator Facility (HIAF), has to be optimized for the closed orbit correction system. Since the maximum horizontal β function of the isochronous mode (γ_t=1.43) is very large, the field imperfections and alignment deviations of the magnets will cause large closed orbit distortion (COD), which will result in the distortions of linear optics. Therefore, the closed orbit correction is critical to the operation of SRing. In the simulations, the Singular Value Decomposition (SVD) algorithm is adopted. The repeated correction method is applied and the response matrices are multi-calculated before each correction. The influences of BPM reading errors are analyzed. In addition, the effects of reduced singular values are analytically expressed and simulated. As a result, the closed orbits are corrected to be less than 0.8 mm, and the linear optics is also well optimized.