Four phosphate-accumulating bacterial strains, designated as P1, P2, P3, and P4, were separated from biological sludge in a stably operated AAO system for phosphorus absorption and release experiments. The results show that the four strains had high capabilities of removing phosphate from the waste water, and they exhibited high levels of phosphorus release in the anaerobic stage and phosphorus absorption in the oxic stage. P1 had the most significant phosphorus absorption and release characteristics. The maximum phosphorus removal rates of P1, P2, P3, and P4 were 75. 51%, 8. 77%, 47. 26%, and 30. 19%, respectively. Through sequence analysis of 16S rDNA, it was determined that P1 and P2 belonged to Microbacterium and Bacillus, respectively, and both P3 and P4 belonged to Tsukamurella.