The present paper reports a method based on intermittent flow injection (FI) hydride generation (HG) combined with atomic fluorescence spectrometry (AFS) detection for the determination of As in sea water. Experimental conditions for FI-HG were optimized. 5.0％ hydrochloric acid-0.1 mol· L-1 citric acid solution was selected as the carrier flow as well as the sample medium, and 2% KBH4-0.5% KOH was used as the reductant. An argon gas flow was used for carrying the generated arsine to the Ar-H2 flame for atomization. Organic species of arsenic cannot be generated arsine under the selected conditions. The real sea water samples collected at Zhanqiao seashore in Qingdao and more than 30 other areas were analyzed under optimized working conditions, and experiments verified that the determination of As(Ⅲ) and As(Ⅴ) could approximately assess the As pollution for marine water while organic arsenic in natural sea water was so slight that could be neglected in case large amount of samples should be analyzed.