Nanoparticles are widely observed in the natural shear zone and experimental slip faults, whichcan lubricate the fault and significantly reduce the friction coefficient during seismic slip. But it is still not clear how the nanoparticles develop during the process of sliding. Clarifying the development stage of nano-particles in a fault zone is critical to understanding the formation mechanisms of nanoparticles and the mech-anism of fault weakening from a nanoperspective. In this study, four types of nanoparticles were found in the Indosinian Xiaomei shear zone, including spherical nanoparticles, rod-like nanograins and their aggregations. Ultramicroscopic analyses indicate that polished patches are highly smooth and composed of tightly packed spherical nanoparticles and well orientated rod-like nanograins during slip at high velocities. Meanwhile, the dome nanoparticles were formed by the calcite thermal decomposition due to frictional heat during high-speed sliding. The polygonal grooves are possibly related to high temperature (>900 ℃) grain boundary slid-ing deformation mechanisms. However, the porous and rough surfaces are accompanied by a series of holes and parallel scratches during a subsequent low-velocity stage. To ascertain the chemical composition of these nanoparticles, the energy dispersive spectrometer (EDS) test were conducted. The results suggest that materials rich in Fe, MgO and wollastonite are likely to form the rod-like nanograins, while materials rich in SiO2 are likely to form the spherical nanoparticles.