The invention discloses a pulverized coal accumulation preventing device of a steel ball coal mill and a pulverized coal accumulation preventing method. The device comprises a scraper positioned in a mounting gap between a rotary conveyor and a hot air box, an air blowing hole formed in the hot air box, and a blowing air pipe leaded out from the air blowing hole. The pulverized coal accumulation preventing method comprises the following steps: the rotary conveyor drives the scraper to scrape out pulverized coals accumulated in the gap; and meanwhile, external air is fed in the air blowing hole and the blowing air pipe to blow the pulverized coals scraped out in the previous step into the rotary conveyor of the steel ball coal mill. In the pulverized coal accumulation preventing device of the steel ball coal mill and the pulverized coal accumulation preventing method, the steel ball coal mill is provided with such pulverized coal accumulation preventing devices as the scraper and the blowing air pipe for realizing removal of pulverized coals in the mounting gap between the rotary conveyor and the hot air box under the condition of no stop, so that the machine use efficiency is improved, and the machine operation safety is improved.