Organo-montmorillonite (OMMT)/nature rubber (NR) nanocomposites were prepared by mixing method. The microstructure of these composites was characterized by SEM and XRD. The effect of OMMT on mechanical properties and thermal conductivity of the nanocomposites was investigated in detail. SEM and XRD confirmed the intercalated structure of OMMT/NR nanocomposites. The introduction of a small amount of OMMT greatly improved the mechanical properties and thermal conductivity behavior, which was attributed to the nanometer scale dispersion and stronger interactions between OMMT and NR chains.