The NR/modified montmorillonite (EMT) nano-composites were prepared by mechanical mixing and reacting in situ with glycidyl methacrylate. Under 30 kW·m-2 of heat flux, the combustion behavior of the nano-composites was studied with cone calorimetry, and PHRR, THR, EHC, TSR and MLR were tested. The results showed that the nano-composite had improved mechanical properties and flame retardance properties, and to some extent, the nano-composite had smoke suppress effect. Compared with pure NR, the PHRR, EHC and SPR of the nano-composite reduced by 34%, 21% and 16.8%, respectively.