The present study is to compare and analyze extracts of active substances from larch bark using ultrasonic wave quickly and undamagedly via Fourier transform infrared spectroscopy, second derivative IR spectroscopy and two dimensional spectroscopy. In the spectra of active substances from larch bark, there are four main components as the structural unit, and (+)-catechin, (-)-epicatechin, gallic acid and vitisinol represented a series of poly polyphenolic compounds. Furthermore the linkage between unit in proanthocyanidins dimmers was confirmed at position C(4)-C(8). Through observing the second derivative IR spectra of active substances from larch bark, the absorption peaks, 1 631, 1 561 and 1 469 cm(-1) of active substances moved to the smaller wave number direction, while 1 606, 1 385, 1 285 and 1 157 cm(-1) of active substances moved to the bigger wave number direction, and the intensity of characteristic peaks can represent the content of corresponding compound. In the two dimensional spectra, the active substances from larch bark have five automatic peaks in 1 345-1 675 cm(-1). The authors developed the new method to analyse and evaluate the active substances from larch bark successfully.