Abstract: Using the rainfall data observed by Wuhan mesosphere-stratosphere-troposphere(MST) radar and building a second-order Gaussian spectrum model, we obtained the spectral information of the atmosphere turbulence and rainfall based on the least squares fit. The echo energy and radial motion state of the atmosphere and precipitation particles can be extracted by the spectra of the atmosphere turbulence and rainfall, then the atmospheric 3D wind field can be calculated from five beams and the formation mechanism of rainfall is discussed. Meanwhile, assuming the raindrop size distribution follows the gamma distribution, the raindrop size distributions at different heights are inverted from the rainfall spectrum, and the microphysical process of rainfall in the troposphere is researched.