In order to evaluate existing producing process of larixgmelinii bark proanthocyanidins, understand the changes of the component content in each step, we used Tri-level infrared spectroscopic to identify, which employed the Fourier transform infrared spectroscopy(FTIR), the second derivative infrared spectroscopy(SD-IR) and two-dimensional correlation infrared spectroscopy. The results indicated that the FTIR spectrograms of the product of each process in shape was very similar. We found that some substances characteristic peak disappeared or offseted, reflecting the changes of component content of samples. With the improvement of production process, the purity and structure of samples have been more and more near to the standard sample, but still contained some other substance. The second derivative infrared spectroscopy not only tested and verified the analysis results of FTIR, but also improved the resolution ratio which was helpful to show differences that were not manifested in FTIR. Within the scope of the 830 to 1 310　cm-1,2D-IR has more significant differences in positions, strength and numbers of automatically peaks. Therefore, we could conclude from the Tri-level infrared spectroscopic identification that the purity in proanthocyanidins is higher and higher with the improvement of production process. And the structures of samples we get finally are similar to that of standard sample, but still contains a small number of impurities