Abstract: Six organic borates with different molecular chain length were synthesized and the friction and wear properties of these borates as oil additives were evaluated using a Timken Tester. Gas Chromatography (GO was adopted to investigate the decomposition of the borates, whereas EPMA and XPS were used to study the surface composition and valence state of boron on the rubbed surfaces. It was found that the friction and wear properties of the borates are significantly influenced by the molecular chain length; the longer the chain length, the lower the friction coefficient and wear, and the higher the failure load. GC analyses found that organic borate take place decomposition and give out alkane and alkene during rubbing process.XPS analyses of the rubbed surfaces revealed that the binding energy of Bis increases after rubbing, but no pure B2O3 and FeB are generated. The failure load and the antiwear effect of the borates are related to the ratio of numbers of carbon atoms to numbers of boron atoms on the rubbing surfaces; the larger the ratio, the higher the failure load.