Based on the size distribution of atmospheric aerosols, the scattering characteristics of aerosols at visible and infrared wave band are calculated by Mie scattering theory, the effects of aerosols on the laser transmission attenuation at visible and infrared wave band are discussed. The numerical simulation results show that the scattering characteristics of aerosols are sensitive to the types and size distributions of aerosols; the laser transmission attenuation are affected not only by the refractive index and types, but also by number density of aerosols. The more the number density, the stronger the laser transmission attenuation will be; while the asymmetry parameter is insensitive to the number density, which is mainly influenced by the size distribution. These results are beneficial to evaluate the effect of aerosols on laser transmission, which will promote the application of laser signal transmission, communication and wind measurement by laser.