The seeding operation scheme for testing the effectiveness of artificial modification, including rockets and aircrafts, is designed. The data collected by a laser raindrop spectrometer in the autumn of 2009 are analyzed. The relative distance and position of the rocket operating point and the laser raindrop spectrometer are calculated. For the purpose of facilitating the operational flexibility in application, the results were marked on the Doppler radar map. Through analyzing the data of 5338 minutes in total of the density of raindrops in 10 precipitation processes, it is shown that in 87.6% of cases the raindrop density was less than 500 for autumn mixing clouds, and in very low percentage of cases the raindrop density was above 3000. The raindrop concentration distributions of different processes have a significant difference. The largest density of 6003 was observed on 16 October 2009, which might be influenced by the artificial rain reduction with rockets.