Abstract: Objective: Using the chicory root of Cichorium intybus L. var. foliosum Hegi from Indian as experimental material to optimize the extraction process of crude polysaccharides from chicory root and determin the antioxidant activity in vitro, as well as the molecular weight. Methods: The effects of solid-liquid ratio, water bath temperature and water bath time on the yield of crude polysaccharide from chicory root were investigated. The Box-Behnken optimization combined with Matlab analysis was used to extract the crude polysaccharides from chicory root by hot water extraction. The hydroxyl free radical scavenging ability and reducing power of crude polysaccharide was determined in vitro. After purification, the average relative molecular weights of neutral sugar and acidic sugar were analyzed. Results: The optimal extraction process by single-factor tests and Box-Behnken design optimization test was obtained as follows: Solid-liquid ratio 2.74:100 g/mL, water bath temperature 72 ℃ and water bath time 165 min. At this time, the theoretical predicted value of extraction yieldof crude polysaccharide from chicory root was 40.32%, while the empirical actual value was 39.99%±0.43%, which had no significant difference with the predicted value (P>0.05). Matlab analysis showed that when the extraction time was higher (C=165 min), the solid-liquid ratio was 2.4:100 ~ 3.1:100 mL/g, and the water bath temperature was 70~74 ℃, the extraction yield of crude polysaccharides could get the higher value. The extracted chicory root polysaccharides had hydroxyl radical scavenging capacity (IC₅₀ value was 1.36 mg/mL) and Fe³⁺ reducing power (the absorbance value at 3 mg/mL was 0.21), which all showed a positive correlation with the concentration. In addition, the peaks of neutral sugar and acidic sugar of chicory root measured by HPLC were good, and the acidic sugar peak was high and narrow, which showed high purity. The average relative molecular weights of neutral and acidic sugars were 10072.07 and 2388.13 Da, respectively. Conclusion: The method of Box-Behnken optimization combined with matlab analysis to optimize the extraction process of crude polysaccharide from chicory root was feasible. The extracted crude polysaccharide not only had a high yield, but also had a good antioxidant activity test in vitro. Among the crude polysaccharide from chicory root, the purity of acidic sugar was higher, and the molecular weight of neutral sugar was larger. sugar is larger.