Carrageenan fibers (CAFs) were obtained through the wet spinning technique with barium salt as coagulation bath. The fibers were characterized by limiting oxygen index(LOI), Cone calorimeter(Cone), scaning electron microscopy. energy dispersive spectrometer (SEM. EDS), X-ray diffraction (XRD), thermogravimetry (TG)-differential scanning calorimetry (DSC)-Fourier transform infrared spectroscopy (FTIR) and pyrolysis (Py)-gas chromatography(GC). mass spectrometry (MS)-The results showed that carrageenan fiber (CAF) took on better flame retardancy than calcium alginate fiber (ALF) and agar fiber (AGF). The LOI of CAF was up to more than 50, and the fiber kept red state without flame in the whole Cone process. Some other Cone parameters presenting lower value, such as heat release rate, total heat release, indicated that CAF has good flame retardancy. The sulfate ester combined with barium ion through complexing action of CAF, and they played an important role in the formation of carbon residue and changing the breakup processes of carra. geenan macromolecule. In addition, flame. retardant mechanism could be attributed to sulfonyl free radical, which can combine with hydroxyl radicals rapidly to terminate the combustion reaction. Meanwhile, the dense structure of barium salt layer and hollow fiber structure were also crucial factors of flame retardant performance for CAF.