Based on the theory of heat conduction, a theoretical model of HgCdTe detector irradiated by pulsed laser in relative motion is established. The thermal effects of the detector at different repetition frequencies and moving speeds are analyzed and compared by finite element method. The results show that the energy of the laser is mainly absorbed by the HgCdTe photosensitive layer and the high temperature field is mainly distributed near the interface between the HgCdTe layer and the CdZnTe layer when the HgCdTe detector is irradiated by a repetitive frequency pulse laser under the relative static condition. There is almost no temperature accumulation effect when the frequency is 1 kHz and 10 kHz. While when the frequency is 100 kHz, the peak temperature increases with the increase of the number of pulses, and there is an obvious temperature accumulation effect. The position of the peak temperature shift gradually to the direction of the velocity vector with the movement of the laser spot under the relative motion. From the point of view of damage, the cumulative effect of the damage in the space area can be achieved when each temperature peak is larger than the melting temperature of HgCdTe, and as a result, the damage to multiple detection pixels can be achieved.The thermal effect of the detector irradiated by monopulse laser spot at different moving speeds is analyzed.The faster the laser spot moves, the lower the peak temperature is at the end of the pulse, the smaller of the slope of the temperature rise curve and the slower of the temperature rise.