This study uses an all-atom computational model to investigate the temperature dependent heterogeneity and percolation in a nanofilm system of short linear epoxy chains on a solid graphene surface. The heterogeneity, which indicates having physical characters that vary within the nanofilm, is mainly manifested in distributions of volume, energy and the dynamic properties. Local glass transition temperatures, T(g)s, from above properties depend largely on the separation to the graphene surface, and the glass transition of the nanofilm is asynchronous along the film normal. Distinct T-g increases and decreases are particularly observed in the solid and free interfaces, respectively, compared with the bulk. From the dynamic heterogeneity, percolation effect, which indicates the connectivity of mobile and immobile domains, of the nanofilm is also observed during glass transition by plotting internal atomic mobility distribution diagrams. A multi-stage percolation mechanism based on the glass transition state and the connection state of immobile and mobile domains of the nanofilm is developed. A relatively immobile domain near the graphene surface is observed, even at temperatures much higher than T-g, and it initiates the dynamic percolation. The interconnection of immobile domains after percolation accelerate the transition from the rubbery to the glassy state. (C) 2018 Elsevier B.V. All rights reserved.