Abstract: Low-level wind shear incidences are always related to thunderstorms.An analysis of two wind shear cases at Chengdu Shuangliu Airport on Jul 9th, 2010 with Doppler radar showed that they were caused by a gust front and a sink airflow of Mesoscale Convective Systems (MCS) respectively.Using real-time data from the terminal Doppler radar and auto weather observation stations, we can calculate the speed and height of the gust front, and forecast the time and location of the low-level wind shear.Doppler images of reflectivity and speed can determine the region caused by the downdraft flow, and they are valuable for the identifying and warning of low-level wind shears.