Ninety crossbred weaned piglets “Duroc × Landrace × Yorkshire” aged 28 days were randomly allocated into 3 groups (3 replicates for each group and 10 pigs for each replicate). Pigs in the control group were fed with basic diet, in low-dose group with basic diet plus 0.1% Cordyceps militaris fermented Schisandra chinensis residue and in high-dose group with basic diet plus 0.2% Cordyceps militaris fermented Schisandra chinensis residue for 14 days. Then one pig from each replicate was selected for blood collection by anterior vena cava venipuncture for analysis of the routine blood parameters, peripheral T lymphocyte subgroups and their proliferative activities, as well as the IL–2, IFN–γ contents. Results showed there was no difference in white blood cells (WBC), lymphocyte (LYM), mean erythrocyte haemoglobin concentration (MCHC), platelet count (PLT), mean platelet volume (MPV) and platelet distribution width (PDWcv) (P>0.05) between the control group and the low- and high-dose groups. Compared to the control, the contents of RBC and HGB in high-dose group were significantly increased (P<0.05), the CD4+/CD8+ ratio and proliferation function of peripheral blood T cell in low- and high-dose groups were extremely significantly increased (P<0.01), the serum IFN-γ contents in high-dose group were also increased (P<0.05 or P<0.01), but there was no significant difference in serum IL-2 contents of piglets among groups (P>0.05). It was concluded that dietary supplied with Cordyceps militaris fermented Schisandra chinensis residue improves the immunologic function and optimizes blood physiology parameters of piglets.