Abstract:In order to study the Doppler weather radar characteristics of the 20 July 2009 tornado in Chengde, the CINRAD/CB, weather charts，wind profile radar，and automatic weather station observation data are analyzed synthetically. The results show as follows: Before the tornado, the low level air is wet and warm. Affected by the upper cold vortex，the strong cold air at the middle troposphere descends, and there are strong vertical shears in the upper middle troposphere. There are strong cyclonic vortices from low level to 6.8 km at Doppler weather radar radial velocity products when tornado appears.The top height of the cell, maximum reflectivity, and echo centroid are higher also. VIL value abruptly increases before the tornado appears, but the sustaining time above 40 kg·m-2 is short. Orientation analysis shows that affected by movement and storm structure, the tornadic vortex signature is at the southeast of real tornadic position.