Abstract: The nano-graphite/nature rubber (NR) composites with different sizes of nano-graphite as fillers were prepared. The influence of nano-graphite with different sizes (30, 80, 150 nm) on the properties of nano-graphite/NR composites such as stress softening effect (Mullins effect), Payne effect, the dynamic heat generation and loss factor, were investigated. The results show that with the increase of size of nano-graphite, the effect of nano-graphite reinforcement on nano-graphite/NR composites is obvious and stress softening effect exhibites almost the same upward trend, dynamic loss factor increases while the Payne effect of composites decreases obviously, on the other hand, with the increasing of dynamic loss factor, the dynamic heat generation increases. The fact that the dynamic heat generation of composites closely relates to the filler network can be concluded. The results of SEM and Payne effect analysis demonstrate that the larger size nano-graphite has a good dispersion in rubber, while the smaller size nano-graphite is easy to aggregate.