A novel class of moire fringe patterns in scanning tunnelling microscope (STM) imaging is presented and analysed in this paper. The moire fringe is generated from the interference of the atomic lattice of the specimen and STM scanning lines. Both parallel and rotational STM moire fringes of the surface of highly oriented pyrolytic graphite (HOPG) are investigated. The formation principle and experimental techniques of STM moire fringes are discussed. Nanometre scale resolution and sensitivity are found in the moire fringe patterns. They precisely magnify the STM image of lattice irregularities. A potential application—measuring surface deformation and defects in the nanometre range—is proposed.