Abstract: The concept of damage morphology criterion is eatablished to study how the different failure modes of optical materials irradiated by CW laser appear under different interaction conditions. The analytic solutions of temperature and stress profiles generated during laser he ating are obtained by the way of Hankel transform, then damage thresholds for elastic failure and melting are determined respectively. The dependence of damage form on material properties and laser parameters is evaluated and the simplified relationship is presented to predict the damage form of optical materials irradiated by CW laser. At last, experiment results are presented to prove the validity of the damage morphology criterion.