A liquid chromatography-mass spectrometry method was developed and validated for the quantitative determination of seven triterpenoids, 3-beta-O-alpha-L-arabinopyranosylsiaresinolic acid-28-O-beta-D-glucopyranosyl ester, ziyuglycoside I, pomolic acid, maslinic acid, colosic acid, oleanolic acid and ursolic acid in Pyrola decorata H. Andres. Chromatographic separation was achieved on a Hypersil C18 column using isocratic elution followed by a linear gradient elution of methanol and water as mobile phase. The analytes were ionized by atmospheric pressure chemical ionization source and determined on selected ion monitoring mode. All analytes showed good linearity (r2 > or = 0.9984) within the test ranges and the recovery rates were 94.5% - 103.3%. Satisfactory precision and reproducibility were obtained with relative standard deviation less than 5%. The method was simple, accurate and performed well in application to the determination of twenty commercial samples of P. decorata collected from different regions of China. It could be used for the quality control of both plant materials and preparations of P. decorata.