The Doppler weather radar parameters of seeding and nonseeding clouds， such as echo top， reflectivity， vertically integrated liquid， echo area， etc.， are analyzed before and after weather modification operations by using the Doppler radar detection data and smallscale and mesoscale ground precipitation data. The results show that all the values of the Doppler echo parameters for the target clouds increased after seeding， reaching the maximum in 20 or 30 min, while the enlargement rate of the contrast cloud is smaller than that of the target cloud. The precipitation downwind reaches the maximum in 20 or 30 min， which is corresponding to the changes of radar parameters of the target cloud. While the rainfall intensity and precipitation of the contrast clouds are less than those of the target clouds.