The carrageenan-based flame retardant(KC-FR) was prepared by reverse emulsion polymerization, using carrageenan (KC) as shell material, ammonium polyphosphate (APP) and manganese dioxide (MnO2) as core material. KC-FR was characterized by FTIR, XRD, SEM and EDS. It was proved that carrageenan successfully coated APP and MnO2, and it has microsphere structure. The effects of different KC, APP and MnO2 ratios on the flame retardant and smoke suppression properties of waterborne epoxy resin were investigated. The flame retardancy and smoke suppression of the coating were characterized by limit oxygen index (LOI), vertical combustion (UL-94) and cone calorimetry (CCT). The results showed that the limiting oxygen index (LOI) of EP increased from 19.7% to 29.1%, when the ratio of KC, APP and MnO2 were 2:1:1(flame retardant coating EP2), and UL-94 level reached V-0 level, which indicated good flame retardancy properties. At the same time, comparing with EP0, the peak heat release (pHRR), total heat release (THR) and the total smoke production (TSP)of EP2 coating decreased by 42%, 37% and 46%, respectively, which indicated good smoke suppression properties. In addition, the carbon residue was 33% using thermogravimetric analysis(TGA), which indicated the content of KC in KC-FR was the key to the amount of carbon residue. Analysis of the carbon layer using SEM and elemental analysis (EDS) indicated that the surface carbon layer was more compact of EP2, which indicated the KC-FR played an important role in formation of stable and dense carbon layer.