The natural Jerusalem artichoke inulin was fractionated by ethanol， and the prebiotic activity of different molecular mass inulin was evaluated by simulated digestion environment in vitro， including the proliferation of Lactobacillus plantarum， the rheological properties of fermentation broth and the changes of short-chain fatty acids （SCFA）. The results showed that the proliferation of Lactobacillus plantarum in 10% inulin group was best， the viscosity of fermentation broth was largest， and the content of SCFA was highest. The prebiotic activity of 10% inulin was best than that of natural inulin and 80% inulin. Probiotic microcapsules were prepared by using 10% inulin as wall material to evaluate the stability. The embedding rate， gastrointestinal fluid digestion stability and storage stability of the inulin probiotic microcapsules were determined. The results showed that the microcapsule embedding rate was 71.98%. The dissolution rate was 12% and reaching the maximum after 40 min digestion in artificial simulated gastric juice. The dissolution rate was close to 100% and reaching the maximum in artificial simulated intestinal fluid for 60 min. The storage stability of microcapsules was better than 37 ℃ under the conditions of low temperature 4 ℃ and normal temperature 25 ℃， and the effect was best under 4 ℃ conditions. Therefore， the optimization and application of inulin are conducive to provide a reference for the development of Jerusalem artichoke.