In order to improve the firing accuracy of weapons, a baseline detection method of infrared Telescopic sight with laser scattering characteristics is designed. By fixing the Telescopic sight and using the blackbody to emit infrared laser, an infrared parallel beam is formed after the mirror reflection, and the target image is generated in the field of view of the Telescopic sight. The baseline detection is realized by adjusting the Telescopic sight graduation center to coincide with the target image center. The Bidirectional reflectance distribution function and Kirchhoff approximation theory are used to analyze the scattering characteristics of infrared laser and the influence of wavelength and scattering angle on imaging accuracy, so as to improve the accuracy of baseline detection. Experimental proof: When the incident wavelength is 9.5 μ At around m, the roughness of the shooting target is 8 μ At m, the bistatic polarization scattering coefficient is the lowest, around 1.0; When the scattering angle is around 29°, the roughness of the shooting target is 8 μ At m, the lowest bistatic polarization scattering coefficient is around 0.146; The average deviation of the target position after correction is 0.01 m.