The initial damage threshold, the damage growth threshold and the damage growth laws of K9 glass and fused silica glass are tested respectively in the same experimental condition with 1 nanosecond laser. The comparison of the laser induced damage performance between the two glass materials is performed. The results show that the initial damage thresholds of the two glass materials are the same, the damage area growths both obey the exponential increase rule and their damage depth growths obey the linear increase rule. However, there is apparent difference in the rule of damage growth. For example, the damage growth threshold is lower and the damage growth coefficient is higher for K9 glass. This can be explained by the difference in the material mechanical strength between the two glass materials. The present research is very important for choosing transparent optical materials used in high power laser.