Abstract: Lactobacillus reuteri J1,a probiotic strain isolated from traditional fermented dairy products was used as the research object to investigate on the adhesion property,tolerance in the gastrointestinal environment and its immunomodulatory activity. The results showed that the adhesion rate of L. reuteri J1 was 87.93%. L. reuteri J1 reached the logarithmic phase after 4 h and then reached the stable period after 14 h. In the evaluation of tolerance to gastrointestinal,the survival rates of the strain were 86.77% and 97.12% after treatment in the medium of pH2.0 and pH3.0 for 3 h,respectively. Treated with the bile salt in concentration of 0.3、0.5 and 1.0 g/100 mL for 4 h,the survival rates of the strain were 105.00%,82.60% and 82.18%,respectively. After being cultured with simulated artificial gastric juice for 3 h and then the cells were transferred to artificial intestinal juice for 8 h,the survival rate was 82.71%. In addition,the survival rate was 80.36% after treated with 7 g/100 mL of high-quality salt solution for 24 h. Moreover,10⁸ CFU/mL of L. reuteri J1 could regulate the expression of cytokines interleukin-1β(IL-1β),IL-6 and IL-8. In summary,L. reuteri J1,a probiotic strain with immunomodulatory activity could colonize in the intestinal epithelial cells and tolerate to the environment of gastrointestinal.