It is obtained the relation functions between particle diameter, terminal velocity and drop size distribution based on the data of particle diameter, terminal velocity and particle number detected by laser raindrop monitor. The rainfall intensity is calculated and compared with meteorological data to build error functions. According to measurement error, a precipitation inversion algorithm is developed to calibrate rainfall intensity and amount of precipitation, resulting in reducing 10% error of corrected precipitation amount. At last, precipitation type is distinguished by calculated relative data.