The geometrical structures of 2-(2-hydroxyphenyl) pyridine(PP) and its protonation states were optimized by means of the B3LYP/6-31G(d) method. For all the selected systems, the existence of H-bond is in favor of the stability of the systems. On the basis of the optimized geometrical structures, their electronic spectrum properties were studied by time-dependent density functional theory(TD-DFT) methosd via a hybrid function of B3LYP and 6-31G(d) basis set. The TD-DFT calculation result predicts the absorption spectrum of PP at 324 nm(3.82 eV), which is in very good agreement with the experimental value of 322 nm(3.85 eV) determined in solvent chloroform. The absorption spectra of the two protonation states both exert a red shift in various pH media.