For studying the extinction characteristics of black carbon and black lead sphere particles to the laser of 1.06 μm and 10.6 μm wavelength,extinction coefficient was calculated based on Mie theory,and the transmission rate vs smoke thickness was calculated by using Lambert-Beer theory.Results show that black carbon and black lead particles all have a optimal radius to make the extinction characteristics best.Absorption is dominant for small particles,Scattering and absorption work at the same time for large porticles.Extinction characteristics of black lead sphere particles is better than that of black carbon during 0.05~0.16 μm wavelength.In other warelength range,the extinction characteristics of black carbon smoke screen is better than that of black lead.The transmission rates vs smoke thickness was calculated under the condition of optimal radius.The condusion is aseful in practical field application.