Four proanthocyanidin fractions(F1, F2, F3 and F4) from the red skin of lotus seed were measured for mean degree of polymerization, and analyzed for chemical composition and structure by infrared spectroscopy, reversed phase high performance liquid chromatography(RP-HPLC) and reversed phase high performance liquid chromatography coupled with electrospray ionization mass spectrometry(RP-HPLC-ESI-MS). The results of measurement showed that the mean degrees of polymerization of F1, F2, F3 and F4 were 2.12, 7.27, 7.85 and 8.16, respectively. Their infrared spectra exhibited obviously the character...