Abstract: Both the Stribeck curve and friction coefficient were mensurated before and after the Lα-DPPC was added into the HA lubricate system by pendulum friction apparatus. It was found that the system friction coefficient decreased sharply after Lα-DPPC was added. From the Stribeck curve, the lubricate mechanism of the lubricate system could change from the mix lubricate to the liquid film and mix lubricate. It is speculated that the interface characteristic must be changed because of Lα-DPPC. In order to prove this speculation, surface tension was tested when Lα-DPPC was added into the HA lubricate system, and an analysis of IR spectra was done on Lα-DPPC. The results show that Lα-DPPC has hydrophilic and hydropholic characteristics, and acts as a surface active agent in lubricant, which decreases surface tension greatly. This contributes to film formation in the system and increases lubricate effect.