Abstract: The operation of the reprocessing processes depends not only on the stability of the process and the reliability of the equipment but also on the reliability and timeliness of the analytical technology. Due to the special characteristics of the reprocessing process samples, quantitative chemical analysis of the samples obtained from the reprocessing process is a challenging task. Traditional analytical techniques and methods can no longer meet the analytical requirements of the advanced reprocessing process. Therefore, to improve the speed and accuracy of the analysis of relevant components in the reprocessing process, as well as to reduce the amount of radioactive waste generated, the sampling time, and the risk of radiation exposure of operators, it is extremely important to realize the online monitoring and analysis of spent fuel. The online spectroscopic analysis technology is expected to be applied in advanced reprocessing processes due to its simplicity, information-richness, timeliness, reliability, and non-destructiveness. Currently available spectral analysis techniques include UV-Vis-NIR absorption spectroscopy, Raman spectroscopy and spectral coupling. Due to the special 5f electron orbital configuration, actinides of different valence states(U, Pu, Np) have different spectral characteristics in the visible-near infrared region. For example, U(Ⅳ) at 1080 nm, Np(Ⅴ) at 980 nm, Pu(Ⅲ) at 900 nm, and Pu(Ⅳ) at 815 nm have characteristic absorption peaks, which can be used for the qualitative and quantitative analysis of actinides. There are a variety of groups with Raman activity in the reprocessed material. In nitric acid solutions, \mathrmUO_2^2+ at 860 cm⁻¹ has a characteristic Raman peak that can be used for qualitative analysis. To reduce the relative error of measurement as well as to simultaneously analyze a variety of components, the technique of UV-Vis-NIR absorption spectroscopy combined with Raman spectroscopy can be used. This review provides an overview of spectroscopic analysis for key elements(U, Np, Pu, Tc) and other species(lanthanides and nitrate) in the reprocessing of spent nuclear fuel. The applications of UV-Vis-NIR spectroscopy and Raman spectroscopy in the development of online spectroscopic analysis techniques are introduced. The advantages, disadvantages, and prospects of the online spectroscopic analysis techniques are also summarized. UV-Vis-NIR spectroscopy data acquisition is suitable for high-speed online monitoring, but the specificity and sensitivity in the near-infrared region are limited. Raman spectroscopy structure analysis ability can be non-destructive in situ monitoring, but its signal-to-noise ratio is relatively low. The prospects of on-line spectral analysis technology was summarized. First, it is necessary to systematically study the chemical species and spectral patterns of different metal ions and establish a standard model to realize accurate analysis. Second, more efficient spectral analysis methods should be developed to meet the challenges of spectral overlap and baseline drift. Third, online devices and software should be further developed to meet the challenges of instantaneous output and analysis of spectral signals under real working conditions.