Laser induced damage in the visible window glass, such as K9 glass, irradiated with Nd:YAG laser operating at 1.064μm wavelength and approximately 10ns pulse duration was investigated in the present experiments. The pulse energy, duration, and beam spot size were taken as changeable factors to study the laser damage results. The experimental arrangement consists of a Q-switched Nd:YAG laser with pulse duration of about 10ns operating at 1.064μm, a lens of 40cm focal length which focus the laser beam onto the sample, a diaphragm to adjust the incident laser energy, a power stabilized He-Ne laser at 0.6328μm providing a diagnostic beam onto the Nd:YAG spot size, a detector which can measure the 0.6328μm reflected from the spot during the pulses beating. Images analysis was conducted at different laser induced damage level. At last, the dynamic damage threshold measuring method was discussed.