Near infrared spectroscopy and interval partial least-squares (iPLS) were applied to rapid quantitative analysis of thepoly-β-hydroxybutyrate (PHB), polyphosphate (Poly-P), and glycogen (Gly) during denitrifying phosphorus removal. Wavelet denoising was used to pretreat the raw near infrared spectroscopy, and the quantitative analysis models (iPLS models) of PHB, Poly-P, and GLY were established with interval partial least-squares (iPLS). The iPLS was used to select the optimal spectral interval for modeling. The total phosphorus decreased from 7.9 mg/L to 0.67 ma/L during denitrifying phosphorus removal. The region from 4,320 to 4,640 cm -1 was selected to establish the iPLS model of intracellular PHB. The region from 4,000 to 4,320 cm -1 was selected to establish the iPLS model of intracellular Poly-P.Finally, the region from 5,103 to 5,379 cm -1 was chosen to establish the iPLS model of intracellular GLY.Statistical tests of these iPLS models of PHB, Poly-P, and GLY show that the correlation coefficients show that the proposed models may provide a rapid and effective quantitatively analysis of intracellular PHB, Poly-P, and GLY, and that the effect of the denitrifying phosphorus removal process can be quickly judged from the cell metabolism perspective.