AbstractA grading countercurrent extraction method was used to separate polymeric proanthocyanidins (LPPC) from degreased Larix gmelinii bark, and the purification of LPPC was performed using HP-2MGL resin. The purity of LPPC was 26.37%. The cumulative recovery rate of purified product (LPPC-1) was 98.54% by the adsorption method of HP-2MGL resin. The purity of LPPC-1 was 99.79%. Catalytic hydrogenolysis tests of LPPC-1 were performed by means of a palladium carbon catalyst. The degradation rate was 67.5%, and the residual rate was 72.1%. The results of antioxidant ability showed that the degradation product (LHOPC) had more excellent antioxidant ability compared with LPPC-1, VC, TBHQ, grape seed extract, and pine bark extract. The results, through the analysis of the linear model of MALDI-TOF/TOF MS, revealed that LHOPC was oligomeric with the tetramer as the major component and the distribution ranging from the trimer to eleven units.