A Bacillus was isolated from the sludge contaminated by coke-plant water for a long time. Its degradation effects and growth curves on anthracene phenanthrene and pyrene were tested. Under the conditions of single PAH existence, the Bacillus was the most effective on the transformation and degradation of anthracene and the least on phenanthrene within 82h. After 106h reaction, the concentrations of each PAH was almost zero. In the mixing system of anthracene phenanthrene and pyrene, phenanthrene was the most competitive for transformation and degradation, and pyrene was the least. The degradation of pyrene with the Bacillus can be accelerated by rinsing-rice-water. The Bacillus can grow in above reaction system. The highest density of colony-forming units (CFUs)/ml was 16500 times as that of the original one in phenanthrene system, 4210times in anthracene system, 920times in pyrene system.