In order to further research damage mechanism of HgCdTe crystal irradiated by high repetition frequency CO2 laser. Temperature experiment of HgCdTe crystal irradiated by high repetition frequency CO2 laser is conducted, and temperature rising progress of HgCdTe crystal irradiated by different repetition frequency CO2 laser (1、5、10 kHz) are measured. Theoretical model of HgCdTe crystal irradiated by high repetition frequency CO2 laser is developed, and the impact of laser repetition frequency on temperature characteristic is analyzed. The impact of thermal stress on damage characteristic is analyzed basing on scanning electron microscope (SEM) damage morphology and the value of temperature rising and thermal stress calculated by ANSYS. The research results show that temperature of the crystal irradiated by high repetition frequency CO2 laser gradually rise with increasing of irradiation time, and thermal equilibrium should have been attained on the Hg0.826Cd0.174Te crystal when irradiation time is 10 s. When repetition frequency is more than 1 kHz, the temperature mainly depends on laser average power density，and doesn′ t depend on repetition frequency. The maximum thermal stress is 5 × 107 Pa when Hg0.826Cd0.174Te crystal surface melts，the value of which is less than the ultimate stress. The conclusions have a reference value for laser protection on high repetition frequency CO2 laser.