Photoionization dynamics of β-alanine is studied by the trajectory simulations using the ab initio potential energy surface. Vertical photoionization in the spirit of the Franck-Condon principle is assumed both for the adiabatic and thermostatic simulations. Both intramolecular proton transfer and fragmentation while only the proton transfer are found in the thermostatic and adiabatic simulations, respectively, for the conformer having the intramolecular hydrogen bond N…H-O. The theoretical predictions are in line with the experimental observations available in the literatures. It is reported for the first time that the thermostatic temperatures strongly affect the fragmentation processes induced by photoionization.