Abstract： Objective To observe and analyze the effect of B. Adolescentis and L. Acidophilus on the proportion of Th cell Th1/Th2 in peripheral blood of UC-mice in acute stage and recovery stage. Method 40 BABL/c mice were induced by 3% DSS water for 7 clays free drinking and then with distilled water for 10 days. They were randomly allocated in 4 groups: NS group, SASP group, BF0624 group and LT0637 group, also the fifth group-10 normal animals. The blood of mice were collected by removing their eyes at day 8 and day 18, and then the mononuclear cells were iso]atecl. The proportion of Th1/Th2 was analyze through flow eytometry,hy labeling the specific antibody ot Th cellular membrane with the CD4 antibody, and the cytoplastie antigen of Thl or Th2 with IIA antibody or IF'N-γ antibody. Result The proportion of Th1/Th2 in normal mouse was 0. 84 -0. 94,and it raised up in DSS-mice at both acute stage and recovery stage. It decreased unequally after 7 or 17 days'B, adoleseentis, L. Acidophilus and SASP treatment, but that of all three groups were lower than NS group (2.21±0. 83). Even the proportion got close to the normal animals after 17 days'L. Acidophilus -treated. Conclusion The proportion of Thl/Th2 increased at the acute stage and recovery stage of DSS-mice. Both B. Adoleseentis and L. Acidophilus had more effective than SASP on decreasing the proportion of Th1/Th2 at two stages,ospecially L. Acidophilus.