Rapid spectroscopy of GRB afterglows is an important and hard task.Based on the archival XS-GRB spectral database,we here perform a pilot study on the afterglow's spectroscopy in the forthcoming SVOM era in two aspects.First,our simulation indicates that the color acquired from the SVOM/VT blue and red channels is effective in discriminating between low-z(z ＜ 3)and distant GRB candidates until z～6.Second,by doubling the sample size,we find that the previously proposed global photoionization response of the circumburst gas to the prompt emission(i.e.,the CIV/CII-Liso/Epeak relationship)is rough-ly confirmed,although the confirmation is dissatisfactory at the large Liso/E2eak end.We believe that this issue can be further addressed in the SVOM era by a larger spectroscopy sample,thanks to its capability of rapid identification of optical candidates of afterglow and its anti-solar pointing strategy.