Objective TO study the cellullar immunity function and the role of interleukin-6(IL - 6) during trauma and its recovery stage. Methods 14 cases of serious and 28 mild traumatic fractureswere selected to observe the change of T cell proliferation reaction and IL - 6 presentation of concentration inthe liqUid of T cell culture in vitro. Results 57.14% of serious cases presented the depression of cellproliferation, and IL - 6 concentration reduced to 82. 36 pg/ml, which was lower than that in mild traumagroup (183. 07 pg/ml) and control group(472. 90 pg/ml) respectively. There is statistical significance between the two groups. The rate of CD 8 + T cell was increased relatively in the serious group (33. 43% ), andthe ratio of CD 4 + /CD 8 + (1.58 ) was lower than the group of mild trauma (1. 73 ) and control group (1. 76).There is negative relationship between the concentration of IL - 6 in cell proliferation liquid and CD 8 + T cellratio (r = - 0. 438) in those cases. ConcluSion in serious cases, the T cell proliferation was depressed,while the number of CD 8+ cell increased relatively, and IL - 6 expression was decreased.