A statistical analysis of 38 rain enhancement cases in Dalian of Liaoning Province is made based on the basic data and products of Doppler radar echo in last two years. The variation characteristics of primary echo parameters are summarized. It is shown that some radar echo parameters varied regularly with time. The radar echo intensity and VIL (Vertical Integrated Liquid water) after seeding became greater, and the maximum values appeared in 20 to 30 minutes after seeding. The evolutionary characteristics of cloudtop heights were different: the heights of stratuscumulus mixing clouds increased，while the heights of stratiform clouds decreased at first and then increased. The results provide useful reference for the seeding effectiveness analysis with Doppler data and the scientific selection of seeding opportunity aiming at largerange and stable precipitation processes, as well as the sufficiency exploitation of air cloudwater resource.