An effective method for the analysis of a new type composite antioxidant has been developed. High performance liquid chromatography (HPLC) with diode-array detection (DAD) interfaced to atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) was used. In this paper, the major components of the composite antioxidant additive were identified by means of HPLC/APCI-MS with positive/negative ion scan modes and programmable in-source collision induced dissociation and infrared(IR) spectra. The results show that this method is rapid, convenient and very useful for the analysis of lubricant additives.