Abstract: Elevation angle and algorithm design have important influence to the quantitative rainfall estimation of the weather radar. This paper puts forward a dynamic ab value based quantitative rainfall estimation algorithm. And according to the analysis of terrain nearby Chengdu, this paper comes up with mountain avoidance method. Experiments on application of Convective precipitation and Stratiform precipitation indicate that, the average relative error decreased by 14. 5% and 10. 8%respectively. Experiments on Reflectivity factor of 7 contour planes with different height in 0. 5~3. 5km section by using Convective precipitation, Stratiform precipitation and mixed precipitation with rain gage measurement data shows that, average relative error at 0. 5km are optimal. Quantitative rainfall estimation experiments on precipitation processes of 2008 and 2009 shows better result when the precipitation amounts larger than 5. 0mm, and the average relative error is 35. 7%。