Based upon 3 pairs of cumulus in the Jianghuai area cumulus cloudsee ding experiment，a contrast anal ysis of echo characteristics of CINRAD between the target cloud and the referenc e cloud was performed．It was found that the average lasted time of the target c loud was 51.2% longer than that of the reference cloud and the average echo area of the target cloud was 17% larger than that of the reference．And the average water content of per volumn scanning of the target cloud was larger than that of the reference, with a difference of 46% between the target cloud and the refere nce in the whole life time of clouds． It concluded that the seeded could increa se the area of echo, prolong the lasting time of the echo, and increase the wate r content of clouds in its whole life．Besides, from one pair of cumulus, it was found that the time of seeding was rather important for convective cloud. If the convective cloud is situated in its weakening phase, seeding coul d not increase the water content and couldn't prolong its life as well．