Dietary conjugated linoleic acid(CLA) has been shown to affect immune function. Thus, the objective of this study was to investigate the effects of CLA on the mice that treated prednisone. Mice were randomized into 6 groups and fed diet containing either 0(control, P), 0.5%(CLA1, CP1) or 1.5%(CLA2, CP2) CLA for Sweets. Before 1 week of finishing diet supplement CP1, CP2, and P group treated the prednisone by subcutaneous injection. The levels of serum immunoglobulin A, G, E, gut lumen s-IgA, MLN immunoglobulin A, body weight, mucosal protein was compared. The level of serum IgA in CLA1, CLA2, CP1, and CP2 group increased, while which of P group was decreased. The level of serum IgG in CLA 1 group increased, while which of the other group no differences. Serum IgE level showed no difference and the immunoglobulin production in MLN lymphocyte in CLA 1 group increased. The level of gut lumen s-IgA in P group showed decreased, while which of the other group showed no differences. These results support the view that CLA supplement partially enhance the cell-mediated immunity and overcome the immunosuppressive effect of prednisone