A detailed analysis is made of a singlepoint rainstorm on 11 September 2008 over the northwestern plateau of Yunnan Province through Lijiang (CINRAD/CC) Doppler radar data, in combination with the weather background and local topography. The results indicate: on the echo intensity field, there was a mixed precipitation echo composed by cumulus in the front and stratocumulus in the rear; there was an adverse wind area on the velocity field, around the moving path of which heavy precipitation occurred; cold advection characteristics are found at 5.2 km on the VWP map. The subtropical high is relatively strong on 500 hPa, and under the influence of a southward cold air from North China, a shear line moved southeastward on 700 hPa, resulting in the heavy precipitation. The dynamic lifting on the windward slope forced by the special terrain, combined with the wind field on 11 September 2008, is another important cause of the rainstorm.