Abstract: To investigate the effect of infection of different Streptococcus suis strains (HA9801, ZY05719) on the blood biochemical indices and immunological state in Bama miniature pigs，bacterial content and leucocyte of blood were determined after infection, some immunological indexes in the blood were analyzed. Results were as follows: Acute death cases, subacute infection and chronic infection were found after intramuscular injection of Streptococcus suis, the bacterial content of dead pigs reached 106 CFU/mL. Hypersecretion of IL-1, IL-8, TNF-α, IFN-γ were found at 12 hours post infection, the amount of TNF-α, in particular, increased significantly in all infected pigs. Increase of CD8+ and reduction of CD4+ were also found in all infected pigs, the ratio of CD4+ to CD8+ reversed in death cases even, suggesting inhibition of immunity in these pigs. The ability of lymphocyte transformation showed irregular in dead pigs, whereas that of the subacute infectious pigs recovered from a one week-descend after infections. In the first 2 days, the numbers of blood neutrophil reduced in the subacute infectious pigs, and then increasd and reached the peak at 5 days post infection, accompany with reduction of phagocytic ability of neutrophil. The number of blood neutrophil, neutrophil phagocytic ability and lymphocyte transformation ability varied with different prognosis. Our results suggested that the pathogenicity between ZY0571 and HA9801 was different, secretion of the cytokines and changes of the amount of T cell subset and other immunological examination in this research have some associations with the infection progression of SS2.