The molecular dynamics simulation method is used to study the process of silica particle cutting the roughness surface at various cutting depths. The conditions of the asperity and the particle, force bearing state of particle, the distributions of coordination number and temperature in the asperity are investigated. The simulation results show that the material removal rate is small when the cutting depth is smaller than 0.5 nm, and the removed atoms sticking to the silica particle are in single atom or atom cluster form. When the cutting depth is larger than 1 nm, the material removal rate becomes larger; meanwhile a larger scrap is formed. The crystalline silicon is converted into a locally ordered transient structure which is similar to Si-Ⅱ and Bct5-Si with the increases of temperature and pressure in the cutting process; then the transient structure forms amorphous silicon directly as the temperature and pressure decrease after the cutting process.