Based on the data quality control of Chinese new generation Doppler weather radar, an efficient method is proposed to recognize the clear air echoes according to the statistical results of radar data from April to September 2009 in Xuzhou, Jiangsu Province. Different recognition parameters for different radial distance (less than 25 km and between 25 and 200 km） are used to retain the clear air echoes, which can be used as nowcast reference, and remove other nonprecipitation echoes such as superrefractive ground clutters. The velocity data of the recognized nonprecipitate echo area can be employed to estimate atmospheric advection and prediction.