To investigate the impurities in naringin extracted from Citrus grandis 'Tomentosa'.High performance liquid chromatographies coupled with photodiode array and electrospray ionization mass spectrometry detectors (HPLC-PDA/ESI-MS/MS) were applied to investigate the impurities, and their structures were elucidated by spectral data analyses. Quantification was carried out by main component self-compare with correction factor according to ICH guidelines.Rhoifolin and neoeriocitrin were identified as major impurities. The correction factors of rhoifolin and neoeriocitrin were 1.82 and 1.02, respectively tested by HPLC method. The content of rhoifolin ranged from 0.742% to 0.926%, and the content of neoeriocitrin ranged from 0.335% to 0.464%. The gross impurities were less than 1.5%.The categories and quantities of impurities in naringin product are relatively stable. The research provides a way of specification and verification for the analysis of impurities and objective evidence for security assessment of naringin product.