Abstract: The friction and wear properties of N containing heterocyclie compounds (pyridine, pyridine, pyrazine, pyrazine and triazine), which have the same cyclic structure except for the number and the position of N atoms, added to liquid paraffin were evaluated using a four ball machine and a SRV machine. X ray photoelectron spectroscopy(XPS) was used to examine the binding energy of N 1s on the rubbed surface. The results indicate that the effect of above compounds on antiwear properties is improved with the number of N atoms increasing, and N elemnets exist in the boundary lubricating film mainly as oryanic amine(RNH 2) and nitrites. The mechanism discussed in this paper is connected with the different bond length and resonance energy of those N containing heterocyclic compounds.