A supercell storm is analyzed with the Guangzhou Doppler Weather Radar data. The storm occurred on 1 July, 2004 in Zhaoqing, Guangdong Province. There were two outflows lying to the southwest and southeast of the hook echo, respectively. The corresponding low to middle levels radial velocity maps showed a mesocyclone, with rotation velocity about 12m·s^-1. It was a right moving supercell storm moving to the right of the mean wind by 30°.