The laser damage resistance of KTP crystal affects its application in the high-end solid-state laser systems. This study performs the simulated and actual experiments of laser-induced damage of KTP crystal using the laser with wavelength of 1.064μm, repetition rate of 10Hz, pulse duration of 10ns and two spatial distribution beams (i.e., Gaussian beam and flat-top beam). Results indicate that the power density reaches 1.78GW/cm2 and 2.28GW/cm2 respectively when crystal damaged at a single shot test of flat-top beam and Gaussian beam. The actual laser-induced damage experiments show that the flat-top laser beam causes the obvious ablation morphology in the bulk of KTP crystal while the Gaussian beam causes the typical nanosecond laser damage morphology: the pits caused by melting and the small white spots visible to the naked eye. In addition, the color in the edge of the damage region changes in case of flat-top beam.