The radar data,collected from the field experiment of the national fundamental program entitled‘Mechanism and predict theory of disastrous weather over China',in the middle and ower reaches of the Changjiang River in the summer of 2002,are analyzed by the inter-comparison of the PPI and CAPPI echo intensities nearly simultaneously detected by the different radars but covering the same region. Four cases for such inter-comparisons are given out. The first two cases were observed at 05:00 BJT on June 21st,and at 03:00 BJT on June 24,2002 respectively,using the S-band radar in Hefei,and C-band radars in Maanshan and Wuwei,Anhui Province,the lower reach of the Changjiang River. The last two cases were observed at 00:00 BJT on June 24,and 05:00 BJT on July 23,2002 respectively using the S-band radar in Yichang,and C-band radar in Jingzhou,the middle reach of the Changjiang River. Statistical distribution of the echo intensities in each inter-comparison has a good agreement between the radars in Yichang and Jingzhou,however,pronounced difference among the three radars deployed in the lower reach. This may indicate that problems may exist in their initial calibrations. The low correlation is evident from the scattergrams of echo intensities among different radar observations. It is concluded that the location scheme of these radar data needs to be improved. In addition,the research confirms that the precipitation attenuation correction is need for the precipitation intensity measurement if by C-band radar is used.