An analytical method was developed for the determination of ginkgolic acids in ginkgo biloba extract and its preparations by ultra high performance liquid chromatography-triple quadrupole mass spectrometry. A chromatographic column, Agilent Poroshell 120 EC-C18 (50 mm x 3. 0 mm, 2.7 µm), was used with methanol-l% acetic acid (90 :10, v/v) as the mobile phase. The ginkgo acids were detected by electrospray ionization mass spectrometry in negative mode with multiple reaction monitoring (MRM) mode. Ginkgo acids C13:0, C15:1 and C17:1 possessed good linear correlations in the mass concentration range from 2 to 200 µg/L, with the correlation coefficients more than 0. 999. The mean recoveries at the spiked levels of 5, 20 and 100 µg/L were in the range of 86. 3%-114. 3%, and the RSDs were 0. 5%-13. 6%. The limits of detection and quantification were 0. 003-0. 08 µg/g and 0. 01-0. 19 µg/g, respectively. The method was successfully applied to the analysis of actual samples.