Abstract: The effect of heat treatment on the tribological properties of serpentine ultrafine powders (UFPs) as liquid paraffin (LP) additives were studied. The contact resistance between the tribopairs was measured during sliding to monitor the formation of tribofilm. The morphologies of the worn surfaces and the elements distribution thereon were analyzed by Scanning Electronic Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), respectively. Results showed that a tribofilm of oxide layer, in which alumina and silica particles embedded, was formed under the lubrication of LP with serpentine UFPs, as contributed to its excellent lubricating properties. The surface activity of the UFPs was improved by the heat treatment in a temperature range from 300℃ to 600℃, while the layer structure of serpentine was not changed. Hence, the adsorptive capacity, oxygen releasing capability and film forming ability of the UFPs were increased. As a result, the tribological behaviors of serpentine powders were further improved. The layer structure of serpentine was destroyed and hard phases such as forsterite and enstatite particles appeared when heated at or higher than 850℃, as resulted in the aggravation of friction and wear.