Abstract: In June 2013, there was a report that many flight units encountered wind shear and their take-off was interrupted due to the weather process in operation at Nanjing airport. This process urged several planes to take emergency avoidance, and caused a serious effect on the safety of flight. Besides, because of the hidden and sudden wind shear, meteorological service agencies failed to make an advance prediction that day. This paper summarizes the data of the process of observation, products of local radar in the airport and data of the physical quantity field. From the low-level Richardson number of wind shear, we find that its direction was different from the last simple process of low altitude in surface observation and that the convergence of the shear line caused a strong turbulence near the airport, shaking low flying airplanes strongly, thus making them difficult to operate. From the analysis of the long-time wind shear weather process, we think that low layer shear line transit can cause a long-time low-level wind shear, and when it occurs in the approaching area, the wind shear will be very dangerous for flights. In the discussion of the wind shear mechanism, we find that slight changes of ground observation data, Doppler radar products and the Weather Areo Forecast System (WAFS) numerical forecast products have some reference function to the prediction of wind shear, and it can help forecasters use their judgment, so as to ensure flight safety.