Rain drop-size distribution model is an important factor that affects transmission performance of infrared and laser in the rain.Although many rain drop-size distribution models exist at present,yet it has not formed a common conclusion and there is no basis for model selection in specific applications.That makes some calculations and design work difficult.In view of this problem,the paper starts from the Mie scattering theory,combining theoretical analysis with simulation,to discuss several kinds of raindrop spectrum distribution characteristics.Attenuation characteristics of some typical rain drop-size distribution models are compared.By comparing the analysis results with the actual rain attenuation data,it comes to the conclusion that the L-P model is more accurate for heavy rain and the Joss model is more accurate for light rain.Some conclusions are helpful for choosing model when analyzing optical systems such as wireless optical communication.