The downburst on June 25, 2006 in central part of Shaanxi Province was analyzed with Doppler radar data from Xi’an. The results show that the strong single cell is combined and enhanced to cause a bow echo, leading to the weather with strong wind 33 m·s-1. The height of reflectivity factor core (60dBz ) drops markedly. The vertical column liquid water content is 70kg·m-2. The convergence in the middlelevel of the bow echo is relatively strong. The characteristi cs of convergence in the middle level of Doppler wind field can be seen clearly.