In order to reduce individual deviation, twelve piglets from 2 farrows were randomly divided into 2 groups, 6 piglets each, designated as treatment group and control group, BCG or equal volume of saline solution was administered intramscularly into the piglets when 40 days old, The assay result showed that the proliferation response of peripheral blood T-cell and the bacteriocidal capability of piglets peaked at 7 and 3 days post immunization, and then began to decrease from day 10 and 7, while there was no significant effect on the total number of white blood cell and active T-lymphocyte. In conclusion, BCG could significantly enhance cellular immunity and disease-resistance capability of the weaned piglets.