Different from macro-scale scratch, in nano-scale scratch test, the scratching tip is easily tilted, which may display a considerable change of the friction behavior. The ploughing friction and nanohardness dependent on the tip tilt in nano-scratch test for single crystal gold is studied in this paper by using molecular dynamics simulations. The results show that tilting forward (backward) to the scratch direction has a larger effect on the friction coefficient than the case of tilting laterally to the scratch direction. Scratch hardness is also sensitive to the tip tilting forward (backward), while it is insensitive to the tip tilting laterally. Moreover, the local plastic behaviors near tip (pile-up, plastic area, and dislocation evolution) are also dependent on the tip tilt, which may be a major contribution to the mechanism of the nano-scale wear. (C) 2015 Elsevier B.V. All rights reserved.