Objective To observe the virological and immunological items in peripheral blood of Chinese-origin Rhesus macaques infected with SIVmac251.The normal levels of WBC and CD4+T cell ratio for healthy Chinese-origin Rhesus macaques that suitable for simian AIDS modeling also investigated.Methods Thirty-six Chinese-origin Rhesus macaques were intravenously infected with SIVmac251.Blood samples were collected at 10 time points respectively include 1 day before SIV infection,every week within 1-8th week and then in tenth week post infection.Blood routine,peripheral blood T lymphocyte subsets,plasma viral load were tested.Results The most significant changes of the tested items were appeared in 1 or 2 weeks post SIV infection,while the WBC counts didn't show marked changes in all the time points tested.WBC counts ranged from 4×106/ml to 10×106/ml and the CD4+T cells ratio high than 25％ are the suitable levels for simian AIDS modeling.Conclusion This research provides necessary and beneficial informations to the usage of Chinese-origin Rhesus macaques in AIDS research.