The Rydberg state of SO2 has been studied experimentally using the technology of resonance-enhanced multiphoton ionization (REMPI) spectra, where a wavelength tunable high-power pulse laser is used as the excitation source. The REMPI spectra similar to atomic absorption spectra of alkali metal have been obtained in the range of 420~540 nm. The ionization peaks appearing at 429.3 nm and 452.3 nm correspond to the (4+1) REMPI, and the ionization peak at 529.4 nm corresponds to the (4+2) REMPI. The higher electronically excited state appearing in the spectra should be assigned to the Rydberg state series converging to F1A2 with an np orbital (n=4, 5, 6). The scanning of the ionization peak with high precision at 529.4 nm shows that the spectral structure with nearly equal interval corresponds to the REMPI series of 4p（0, v2, 0） Rydberg state of SO2. The harmonic frequency of bending vibration levels of 4p Rydberg state Δν2 is calculated to be (387.3±12.4) cm-1.