Abstract: In large-area laser surveillance, the primary focus is on detecting light scattered by the atmosphere. Aerosols scatter laser light much more effectively than atmospheric molecules. This paper introduces Mie scattering theory and the mass concentration spectrum distribution of urban aerosols. Based on this, the scattered light intensity of urban aerosols is calculated using Mie scattering theory. The calculation results show that the light intensity scattered by aerosol particles with a peak value of 1.0 μm is much greater than that scattered by aerosol particles with a peak value of 4.5 μm. Keywords: MATLAB, Mie scattering, aerosol, laser alertness Abstract: In large-scale laser alertness, the effect of laser scattered by the atmosphere is crucial. The effect of scattering by aerosol is greater than that by atmospheric molecules. Mie scattering theory and the quality thickness distribution of aerosol are introduced. The luminosity scattered by aerosol is calculated. The result indicates that the luminosity of aerosol particles at a 1.0μm peak in the distribution curve is more intense than that at a 4.5μm peak. Key words: MATLAB, Mie scattering, aerosol, laser alertness 1 Introduction MATLAB is one of the most influential and dynamic software programs in the international scientific community today. Originating from matrix operations, it has developed into a highly integrated computer language. It provides powerful scientific computing, flexible programming flows, high-quality graphical visualization and interface design, and convenient interfaces with other programs and languages. MATLAB plays a significant role in universities and research institutions worldwide. Atmospheric aerosols are systems composed of atmospheric medium and solid or liquid particles mixed in it. Data shows that [1] when a 1.06 μm laser beam propagates in the atmosphere, atmospheric molecules absorb and scatter it very weakly, while atmospheric aerosol particles have a more significant absorption and scattering effect on it. For details, please click: Research on Laser Warning Method Based on MATLAB