A highly sensitive and specific liquid chromatography-tandem mass spectrometric (LC–MS/MS) method has been developed and validated for the identification and relative quantification of ten oxysterols in human serum. After alkaline hydrolysis and derivatization, oxysterols in 50 µL human serum were extracted and converted to corresponding picolinyl ester derivatives. The freshly prepared samples were analyzed by LC–MS/MS in high efficiency; and these ten oxysterols were separated within 11 min. The method enabled the determination of standards with limits of detection between 0.0048 and 0.14 ng/mL. The variances between sample preparations and measurements by this method were 3.28–8.47% and 2.01–7.26%, respectively. Recoveries of the oxysterols and cholesterol ranged from 90.49 to 121.01%, with the mean recovery of 102.63%. The rapid LC–MS/MS method enables relative quantification of oxysterols in human serum under high-throughput conditions. Furthermore, the established method has been applied to analyze the content of ten oxysterols in serum of healthy people and atherosclerotic. The results showed that the levels of 25-hydroxycholesterol and cholestane-3s,5α,6s-triol in patients were significantly different from healthy people. This current method might provide the opportunity for clinical application.