Friction-induced selective etching has advantages of low cost, simple operation, and low destruction, thus it is regarded as an important route to realize micro/nanofabrication on monocrystalline silicon surface. To investigate the mask effect of friction-induced mechanical scratch in micro/nanofabrication of silicon surface, the topography and height of line/area structures under mechanical scratch were studied in selective etching and compared with that under oxide layer. It was found that there was no significant difference in mask effect of mechanical scratch and oxide layer, and corresponding evolution mechanism of topography under two different masks was discussed. Finally, the fabrication of composite nano-patterns was achieved by combining mechanical scratch and oxide layer. The present study provides an important theoretical basis for the high-quality and controllable processing of silicon surface, which is based on friction-induced selective etching.