The methods to destroy developing convective clouds, using artificially generated downdrafts, were theoretically justified and thoroughly tested under laboratory and field conditions. It is based on artificial initiation of downdrafts in convective clouds by releasing large doses of powdered agents into their tops. Beijing Weather Modification Office developed a new seeding device to release large doses of powdered agents in field experiments. This is the first device that seeds powdered agents by airdropping in the weather modification field experiments of China. Pollution to the aircraft could be relieved when releasing powdered agents with the device. The powdered agents should be packaged with special box before airdrop. The new device was used at Beijing Olympic Games and Paralympic Games opening and closing days. The total 34 tons of hygroscopic powdered agents were released in 9 flights.