Using Puyang CINRDA/SB Doppler radar detection data, conventional data, intensive operational data, this paper analyzed a tornado process that occurred in Puyang on 16 July 2009. The diagnostic results show that the tornado occurs in the northwest of subtropical high edge, the left front of low level jet and near the warm shear line. Before the tornado there are powerful convective instability energy in atmospheric environment, and large wind vertical shear and abundant water vapor in lower levels. In the Doppler radar reflectivity factor chart, the north of mobile bow echo is strongly developed into hooked echo, and the tornado is detected near the weak echo area. Radial velocity diagram shows there is a meso γ scale cyclonic vortex field with convergence. The strengthened vortex leads to the central tornado vortex, producing the tornado weather. In addition, the strong echo, low echo top high, lower strong vertical wind shear are all the characteristics of Doppler radar products.