The photoionization and dissociative channels of gas-phase hydroxyacetone(HA) are investigated by using vacuum ultraviolet synchrotron radiation, photoionization reflectron time-of-flight mass spectrometer(PI-TOF-MS) and quantum chemistry calculation methods. The ionization energy(IE) of HA,(9.78 ± 0.06) eV, and the appearance energies(AEs) of the major fragment ions C3H5O2+, C3H5O+, C2H5O+, C2H4O+, CH3CO+, CH2OH+, COH+, C2H3+ and CH+3 are obtained by measuring photoionization efficiency(PIE) curves in the photon energy region of 9.5～15.5 eV. Quantitative calculation is carried out by G3B3//B3LYP/6-311++G(d,p) combination method. The reactants, transition states and intermediates related with the molecular dissociation process and the optimal product structure and single point energy are obtained. According to the measured ions appearance potential, the photoionization dissociation channel and mechanism of HA are analyzed combining with quantitative calculation. Results show that the structure rearrangement and molecular ion internal hydrogen atom transfer play an important role in the process of photoionization dissociation of HA.