tThe tubers of Jerusalem artichoke are rich of inulin, which makes the plant one of primary inulin resourcesin China. The aim of this study was to extract inulin from tubers and test the degree of polymerization (DP)10 days before flowering to 80 days after flowering. The DP of inulin reaches a maximum of 19 at 50 daysafter flowering. The variation tendencies of inulin content and DP were almost the same, which increaserapidly at the beginning and then decrease gradually at a lower speed. Meanwhile, the effects of inulinon probiotics in yogurt have been evaluated. It indicated that inulin with low DP has higher activities.Experimental data improve the understanding of status change of inulin in whole growth of Jerusalemartichoke tubers in Northeastern China and are instructive to get inulin with different properties.