Abstract: In order to accurately measure spectral response rate of mid infrared photoelectric detectors, the power stability of mid infrared laser must be improved. A novel method of stabilizing laser power was proposed using the technique of light feedback based on Bragg diffraction principle of the acousto-optic modulator in this paper. The optical path design, control electrocircuit and arithmetic were discussed particularly, on this basis, a mid infrared laser power stabilizers was fabricated. Using this power stabilizers, the power stability of He-Ne laser at a wavelength of 3.39 m was compared. The experimental result shows that this method can improve the power stability of the infrared laser from 8% to 0.4%, and meet spectral responsivity of the infrared detector parameters.