Abstract: The isobutylene-isoprene rubber(IIR) composites were prepared by the melt blending method containing nanoparticle fillers with different morphologies and structures including organomontmorillonites (OMMT)，silica aerogel and precipitated silica. Microstructures of the IIR composites were characterized via SEM and XRD. Effects of nanofillers on the mechanical properties，mustard protection and flammability of the composites were also investigated. The results show that the IIR composites reinforced with 15 wt% nanometer silica aerogel have the best mechanical properties and the tensile strength and tear strength are 9 and 2.2 times greater than those of the pure IIR vulcanizate. The mustard protection of the composites has close relation to particle shapes of nanofillers. Compared with the composite reinforced with sphere like silica aerogel or precipitated silica，the plate-like OMMT/IIR composites show more out standing mustard protection and offer over 21 hours protection against mustard when 15 wt% OMMT is added. Unfortunately，nanofillers do not exhibit remarkable flame retardancy in experiments and oxygen indexes and oxidative decomposition temperatures of the composites only increase a little compared with the pure IIR vulcanizate.