The surface states of scintillator will affect its scintillation performance such as fluorescence emission intensity and spatial resolution, and then affect the test results of radiation detection system. By means of theoretical simulation and experimental research, this paper systematically explored the spatial distribution of fluorescence intensity of LYSO∶Ce scintillator under four surface states (two sides polished, exit side polished only, inlet side polished only and two sides unpolished) when excited by radiation, and the influence of scintillator thickness on its spatial resolution. The results show that the relative fluorescence intensity of the four states at 0° normal direction is 0.49∶0.64∶0.89∶1, and the fluorescence intensity gradually decreases with the emission angle increase. As the surface polished degree decreases, the spatial distribution of fluorescence emitted from scintillators becomes uniformly. When the thicknesses of the scintillator are 0.3, 1.0 and 5.0 mm, the spatial resolutions of two sides polished are 1.70, 1.36 and 1.12 lp/mm, respectively. The spatial resolutions of exit side polished are 1.5, 1.2 and 1.0 lp/mm, respectively. The spatial resolution decreases with the scintillator thickness increases, and the spatial resolution of two sides polished is improved by about 12% compared to exit side polished only.