Using sodium tripolyphosphate (STPP) as core material and chitosan (CS) as wall material, the flame retardant microcapsules CS@STPP were successfully prepared by ionic gel method. The surface morphology and chemical structure of the microcapsules were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The effect of synergistic effect between CS@STPP and expandable graphite (EG) on flame retardant performance of NR/EUG rubber was investigated by adding CS@STPP and EG to natural (NR)/ EUG rubber in a certain proportion. The flame retardancy of FRBR was analyzed by limiting oxygen index (LOI), vertical combustion test (UL-94) and cone calorimetry (CCT). The results showed that the combustion performance of FRBR decreased significantly,LOI reached 28.4%,UL-94 reached V-0 grade, and the maximum heat release rate decreased by 30%.