In the operation of the machine, the tribological properties of the lubricant are apt to deteriorate with temperature elevation. Therefore, it is of great significance to seek a lubricant additive with good high-temperature tribological properties. In this study, the tribological properties of nano magnesium silicate hydroxide (MSH) as a lubricant additive were investigated at 40–200 °C and the results show that the sliding surface lubricated by PAO10 with MSH as the additive can nearly achieve zero wear. The worn surface was characterized by the Scanning electron microscope, Raman spectrometer, and X-ray photoelectron spectrometer. The analysis results show that the electrostatic adsorption between [Si4O10]4− released from MSH and steel surface contributes to the formation of SiO2 film; whereas ion exchange reaction between the phase transformation product of MSH in the contact zone and steel surface results in the chemical bonding Si-O-Fe, and the existence of the bonding facilitate the formation of the protective tribofilm with strong adhesion at high temperature.