The invention discloses a mountain small watershed radar quantitative rainfall estimation technology in the technical field of convective disaster weather monitoring. The technology comprises the steps of S1, building a membership function, and obtaining Z-R relation statistics of different rainfall types; S2, judging the echo type, and removing non-rainfall echoes; S3, carrying out precipitation type division; S4, carrying out rainfall inversion through echo observation of different rainfall types and Z-R relation statistics of different rainfall types, and generating a single-station radar quantitative rainfall estimation product; and S5, generating a radar precipitation rate puzzle product according to the precipitation puzzle and the radar reflectivity. According to the mountain small watershed radar quantitative rainfall estimation technology, through processing in five aspects, namely, reflectivity factor quality control, rainfall type classification, radar mixed elevation reflectivity calculation, Z-R conversion relation and radar puzzle, the precision of a mountain small watershed weather radar QPE product is improved, and the mountain small watershed weather radar QPE product can better serve rainfall forecast and early warning of hydrological and geological disasters.