A Pr-chelate-doped Polymer Optical Fiber (POF) is fabricated．Absorption and emission spectra of Pr³⁺ ions in Pr(DBM)₃Phen-doped Polymethyl Methacrylate (PMMA) have been investigated．Based on modifed Judd-Ofelt theory, the intensity parameters of Pr3+ in PMMA are calculated to be Ω₂=46.334×10^-20 cm²，Ω₄=18.897×10^-20 cm²，Ω₆=1.610×10^-20 cm². The intensity parameters are used to calculate the radiative lifetimes of ³P₀ and ¹D₂ levels, the radiative transition rates and the fluorescence branch rations β. At the same time, the stimulated emission cross-sections σ_ij (³P₀→³F₂, ¹D₂→³H₄) are calculated. Analysis reveals that Pr (DBM)₃ Phen-doped PMMA is promising for use in polymer optical fiber amplifier and laser.