Abstract: Objective:To observe the effects of acute high-intensity interval training (HIIT) on peripheral T lymphocyte cell distribution and immune response in male jnveniles.Methods:Twenty healthy male juveniles performed a bout of HIIT.Leucocyte subset distribution, in vitro T lymphocytes stimulation test (phorbol myristate acetate/ionomycin) induced immune response related markers (CD69, CD40 L, CD122, GARP, LAP, GITR, CTLA-4 and CD39) relative expression level (by median fluorescence intensity (MFI) and positive cell rate) by flow cytometry, plasma stress hormone (cortisol, epinephrine and norepinephrine) by immune analytic method were determined before, immediate after and 60 minutes after completion of exercise.Results:17 of 20 subjects completed all tests.1) lymphocytes and the attendant subsets increased immediately after HIIT (P<0.05) , while decreased 60 min after HIIT (P<0.05) .2) The lymphocyte count immediate after exercise were positively correlated with plasma epinephrine (r=0.84, P<0.05) and norepinephrine (r=0.62, P<0.05) .3) Immediately after exercise, CD40L (CD3⁺CD4⁺ and CD4⁺CD45RO+Th) , CD122 (CD3⁺CD8⁺ and CD3⁺CD8^highT_c) and LAP (CD4⁺CD25high CD127lowTreg) expression upregulated (P<0.05) ;60 min after exercise, CD40 L and CD122 restored (P>0.05) while CD69 of lymphocyte subsets as well as LAP/GARP and CD39 of Treg cell expression elevated (P<0.05) .Conclusion:An acute of HIIT could 1) lead to transitory perturbation of endocrine-immune system and elevation of catecholamine induce lymphocyte subset redistribution by biphasic response;2) selectively mobilize Th and CD8 highT cells and enhance sensitivity to in vitro stimulation-induced immune response, subsequently immunosuppressive Treg were mobilized during recovery to regulate and restore T cell homeostasis.