Abstract: To develop one kind of biologically active agents for improving ability of animal resistance to disease , nonspecific transfer factor（nTF）from yak spleen was extracted by freeze-thaw-dialysis method, then the effects of yak nTF on mice lymphocytes transformation and proliferation were checked by MTT method. The dates showed that: the effects on mice spleen lymphocytes transformation and proliferation produced by group(Lymphocytes+ ConA +TF) were better than that by group(Lymphocytes + TF) or group(Lymphocytes + LPS+TF) (P<0.05); The effect of yak nTF injection on mice spleen lymphocytes transformation and proliferation was better than that of physiological salt solution injecting (P<0.05). The dates presented yak nTF had obvious effect on mice lymphocyte proliferation, and this effect would be enhanced by cooperating with ConA or LPS.