Resonance enhanced multiphoton ionization(REMPI) dissociation channels of acetone were studied using REMPI-TOF-MS and mass-selected excitation spectra in the range of 280—286.5nm. The mass-selected excitation spectra of fragment ions were analyzed and identified. It was shown that the main dissociation channel of acetone is the photoionization of parent molecule firstly in the range of 280—286.5nm, then followed by photodissociation of the parent ion.