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Using the data from surface observation, radiosondes, AWSs, Doppler radar and NCEP reanalysis, the mechanism of the wind shear event is analyzed. The results are as followings: (1) The main reason of the lowlevel wind shear at Hefei Airport was the turbulence at the bottom of the mesoγ scale convective cell, which was caused by the convergence of the northern gust front and the mesoscale convergence line. The downdraft produced by the rapid extinction of multiple mesoscale convective cells strengthened the surface mesoscale convergence line. The gust front and mesoscale convergence line caused the lowlevel wind shear at the airport. (2) The atmospheric stratification was unstable in the northern Anhui before the wind shear occurred. The wind field convergence at 925 hPa provided a triggering mechanism for the strong convective weather, and the easterly flow passing through the Yellow Sea brought enough water vapor to the lower layer. The development and elimination of the severe convective storm in northern Anhui was the fundamental reason for the occurrence of the northern gust front. (3) The midlevel dry and cold air behind the storm hindered the warm air rising, promoted the sinking of the cold air inside the storm and the vertical momentum exchange, which made the outflow intensity of the ground layer enhanced. The two rapid drops of the core height of strong reflectivity factor were the direct cause of the occurrence of the northern gust front.