The resonance-enhanced multip hoton ionization (REMPI) spect rum of 2-but anone in 467～488nm was obt ained using multiphoton ionization-time-of-flight mass spect rometric technique and dye laser. By analyzing the spectrum, we have ascert ained that thest rongest peak in the REMPI spectrum, 62305cm-1, could be at tributed to one component of the 3d Rydberg transition, the peaks in 63291～63898cm-1 are mixed Rydberg-valence vibronic transitions, and 63291cm-1 is the 0-0 transition of the state.