The rovibronic structure on the first electronic excited state (S₁) in gaseous pyridine was studied in its (2+3) polarization resonance multiphoton ionization (PRMPI) spectra excited by circularly and linearly polarized laser respectively. In the spectra, double-peak rovibronic bands were mostly observed. The result indicates that all the vibronic bands were assigned to various mixed-frequency bands of ν6a, ν10a, ν12, ν16b and ν17a in S1 and ν9a in S0. It is assigned that the frequency of ν17a in S₁state is 670 cm-1, and the ν17a frequency decreasing in S₁state is attributed to the similar mechanism undergone by ν10a.