Hydroxyl magnesium silicate powders were prepared by planetary-milling machine and a certain amount of No.46 mechanical oil was canned into the stainless steel vial in order to investigate its influence on the size of particles. The tribological properties of the powders in the oil were investigated on a four-ball machine. The morphologies and the chemical components of the worn surfaces were characterized by means of scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The ball milling results showed that the adding of mechanical oil decreased the cold welding and agglomeration, finally, fine silicate powders of 2μm in mean size were made. The tribological test results showed that the extreme pressure and antiwear properties of No.46 mechanical oil were improved by the additive obviously. The lubrication mechanism is inferred that a boundary lubrication film is formed and the tribochemical reactions occur on the friction surfaces due to the active agents in the silicate crystal, thus it can be seen that the silicate powders is a new and enviroment friendly lube additive.