Dual-polarization radar is able to effectively retrieve raindrop size distribution (DSD). However, as the wavelength of X-band radar is short, larger rain attenuation is observed. This paper makes corrections in reflectivity and differential reflectivity using the self-consistent algorithm with constraints. By conducting scattering simulation and gamma spectrum fitting, the functions of dual-polarization radar and raindrop spectrum parameters are examined to determine the internal relationship of raindrop spectrum parameters for retrieval of DSD. The observed DSD is compared with DSD retrieved by radar and corrected radar parameters. The results show that the method established in this paper is effective for retrieving DSD. The concentration, scale, and spectral shape are improved by using corrected data. Moreover, the vertical structure and horizontal distribution of DSD parameters can be obtained by using range-height indicator and Plan Position Indicator data to retrieve the DSD. Therefore, this method can be used to effectively analyze precipitation.