Arsenic(As) content and its species in porphyra in Fujian province were systematically analyzed by high performance liquid chromatography with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Moreover, arsenosugars were identified by their accuracy molecular weight using quadrupole - time of flight mass spectrometry (QTOF-MS). The results showed that total arsenic content varied from 12.2 to 50.4 mg/kg in porphyra. The arsenosugar was the major As compound in porphyra, and arsenosugar PO4average content accounted for about 60.7% in extractable arsennic samples, followed by AsB (28.4%), arsenosugar OH (6.2%), AsC (2.8%)and DMA(1.6%). In addition, arsenite (AsⅢ) was not been detected in all 60 samples, and arsenate (AsⅤ) concentration was only between 0.06 ~ 0.79 mg/kg in 18 samples, which showed that the arsenic content in the porphyra would not pose a major danger to the food safety. Furthermore, the processing methods of prophyra promoted arsenosugar transformation from other species. The different periods of harvesting porphyra had no obvious effects on the species distribution of arsenic.