A novel long alkyl chain phenylboronic ammonium derivative (DBBT) was prepared and used as lubricant additive.The tribological behavior of DBBT and blended with ZDDP in a mineral oil (HVI WH150) were evaluated by a four ball tester.The results indicate that the DBBT possesses good oil solubility,anti wear property in mineral oil and has a synergistic effect with ZDDP,but no friction reducing performance can be found.The X ray absorption near edge structure spectroscopy (XANES) was used to characterize the chemical composition of the tribofilms and thermal films generated from DBBT and the blend of DBBT and ZDDP.The compositions of the tribofilms from DBBT mainly contain B2O3,while the compositions of the tribofilms from the combinations consist of B2O3,FeS2,alkyl sulfide,sulfite and a little sulfate.