Display omitted •New ReaxFF reactive force field was applied to simulate the tribochemical wear process at Si/SiO2 interface.•Wear of silicon atoms is due to the breaking of Si–O–Si bonds and Si–Si–O–Si bond chains on the Si substrate.•Interfacial bridge bonds play an important role during the tribochemical wear process.•Higher pressures applied to the silica phase can cause more Si atoms to be removed by forming more interfacial bridge bonds.•Water plays an opposing role in the wear process because of its both chemical and mechanical effects. In this work, the atomic mechanism of tribochemical wear of silicon at the Si/SiO2 interface in aqueous environment was investigated using ReaxFF molecular dynamics (MD) simulations. Two types of Si atom removal pathways were detected in the wear process. The first is caused by the destruction of stretched Si–O–Si bonds on the Si substrate surface and is assisted by the attachment of H atoms on the bridging oxygen atoms of the bonds. The other is caused by the rupture of Si–Si bonds in the stretched Si–Si–O–Si bond chains at the interface. Both pathways effectively remove Si atoms from the silicon surface via interfacial Si–O–Si bridge bonds. Our simulations also demonstrate that higher pressures applied to the silica phase can cause more Si atoms to be removed due to the formation of increased numbers of interfacial Si–O–Si bridge bonds. Besides, water plays a dual role in the wear mechanism, by oxidizing the Si substrate surface as well as by preventing the close contact of the surfaces. This work shows that the removal of Si atoms from the substrate is a result of both chemical reaction and mechanical effects and contributes to the understanding of tribochemical wear behavior in the microelectromechanical systems (MEMS) and Si chemical mechanical polishing (CMP) process.