A method for estimating quantitative precipitation by combining observation data of a weather radar and rain gauges includes: acquiring original accumulated data of rain gauges and original accumulated precipitation data of a weather radar to obtain rain gauge-weather radar data G/R pairs matched in the same grid; calculating an observation error of the original accumulated precipitation data of the weather radar through the G/R pairs, and detecting abnormal data to generate an initial correction factor field; determining whether a distance correlation exists between the initial correction factor field and the observation error, and if yes, adjusting the initial correction factor field, and correcting the original accumulated precipitation data of the weather radar through the adjusted correction factor field to obtain corrected accumulated precipitation data of the weather radar; and if not, obtaining the corrected accumulated precipitation data of the weather radar directly through a mean field bias (MFB) factor.