NBR/montmorillonite nanocomposites are prepared successfully by especial extruding intercalation method, and the relationship between microstructure and property is studied. IR and XRD illustrate the different structures between crude montmorillonite and organic montmorillonite. The results of TEM confirm the nano-structure of composites. The study results show that montmorillonite exhibits obviously reinforcement, and the properties of nanocomposites are superior to those of the rubber with carbon black reinforcing, and when the content of montmorillonite is small, the reinforcing effect is obvious.