Determination of Pu(Ⅳ)and nitric acid plays significant role in nuclear fuel reprocessing plant to control process accurately and timely.Coupling C-T fixed-type grating with InGaAs detector,a new novel analytical system for simultaneous measurement of nitric acid and Pu(Ⅳ)was developed by our working group.After obtaining near infrared absorptive spectra by the spectroscopic instrument,the spectra data Determination of Pu (IV) and nitric acid plays significant role in nuclear fuel reprocessing plant to control process accurately and timely. Coupling CT fixed-type grating with InGaAs detector, a new novel analytical system for simultaneous measurement of nitric acid and Pu (IV) was developed by our working group. After obtaining near infrared absorptive spectra by the spectroscopic instrument, the spectra data