Abstract: In this study, photosynthetic bacteria (PSB) were isolated and purified from marine environmental samples from different areas by double-layer plate coating method and scribing method. Vibrio parahaemolyticus, V. vulnificus and V. anguillarum were used as control. The inhibition of marine photosynthetic bacteria was determined by Oxford cup method, and the degradation of nitrite nitrogen (NO₂ ⁻-N) and ammonia nitrogen (NH₄ ⁺-N) by different strains was determined by naphthalene ethylenediamine hydrochloride spectrophotometry and indophenol blue spectrophotometry. The results show that three strains of photosynthetic bacteria were isolated from 30 sea water and mud samples, and the P-3 strain isolated from the seawater samples of Cheniushan Island in Lianyungang had strong inhibitory effect on three kinds of Vibrio, especially for V. anguillarum, with the inhibition zone diameter of 5.3 mm. The results show that all the three photosynthetic bacteria have certain ability to degrade NO₂ ⁻-N and NH₄ ⁺-N, and P-3 strain had the strongest ability. The degradation rates of P-3 strain were 89.68% and 94.98% respectively, when being cultured in the medium containing 50 mg·L⁻¹ NH₄ ⁺-N and NO₂ ⁻-N for 4 d. P-3 strain was identified as Rhodopseudomonas palustris by morphological observation, physiological and biochemical tests and 16S rDNA sequence analysis.