A fingerprint method for quality assessment of Fritillaria thunbergii was developed by rapid resolution liquid chromatography coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry (RRLC-Q-TOF-MS). The separation was performed using Agilent Eclipse Plus C18 column (2.1 mm x 100 mm, 1.8 microm) by gradient elution with acetonitrile and 0.1% formic acid aqueous solution (containing 10 mmol x L(-1) ammonium formate) as the mobile phase. Q-TOF-MS was used to obtain the accurate mass for precursor and product ions. Under this chromatographic and MS condition, 12 batches of F. thunbergii and its adulterants (F. hupehensis and F. pallidiflora) were analyzed by RRLC-Q-TOF-MS. Fifteen steroidal alkaloids were identified from F. thunbergii, F. hupehensis and F. pallidiflora and nine were assigned as the common characteristic peaks for F. thunbergii. The RRLC-Q-TOF-MS fingerprint of F. thunbergii was different significantly with those of F. hupehensis and F. pallidiflora. The quality of 12 batches of F. thunbergii samples were finally evaluated by hierarchical clustering analysis (HCA) and principle component analysis (PCA). This convenient and high specific method could be used to identify and evaluate the quality of the F. thunbergii.