A heterotrophic bacterial consortium, degrading Phenanthrene(PHE) and oxidizing As(Ⅲ) simultaneously, was isolated from the soil in a discarded coking plant containing PHE and As(Ⅲ). After 48 h incubation, the bacterial consortium removed 71.4% of PHE and transformed 96.2% of As(Ⅲ) in liquid culture containing 200 mg/L PHE and 60 mg/L As2O3 . To validate the dual function of the consortium from molecular level, phenanthrene degrading gene RHDα and arsenite oxidizing gene aoxB were chosed to establish clone libraries. The RHDα genes had high homology with Pseudomonas aeruginosa and Pseudomonas putida, while aoxB genes had high homology with Pseudomonas stutzeri and Alcaligenes faecalis. Real time quantitative PCR results showed that the copy numbers of aoxB genes increased from 3.00×108 to 1.48×1010, while the copy numbers of RHDα genes increased from 2.54×107 to 8.70×109 after 48 h incubation. The dual function consortium showed potentials for practical applications of degrading phenanthrene and arsenic co contamination.