To study the influence of pulse width on the damage threshold of HgCdTe material irradiated by mid-infrared in-band laser pulse, a one-dimensional model named self-consistent model is established. Some parameters including number density of carrier, carrier and energy current, temperature of carrier and lattice are calculated in the whole process. Damage thresholds of in-band single pulsed laser, whose wavelength is 2.85 μm and pulse width ranges from 30 ps to 10 ns, are obtained. The results show that, damage threshold rauge of in-band laser is 200-500 mJ/cm². Among them, the damage threshold of 300 ps to 3 ns laser pulses is about 200 mJ/cm², which is lower than that of other pulsed lasers. The validity of simulation model is verified by setting up the experimental devices and carrying out relevant experiments. Using a single pulsed laser with wavelength of 2.85 μm and pulse width of 300 ps as the light source, the damage threshold is about 200 mJ/cm². Under the same conditions, when 10 ns single laser pulse is used, the damage threshold is greater than 474 mJ/cm². The damage process of the HgCdTe material destroyed by hundred-picosecond pulsed laser combines thermal and optical breakdown effects, and its unique mechanism aggravates the destruction of material.