【Abstract】 Objective To detect the inhibition of XE-TNFαm2 on SIV infection and apoptosis on SIV-infected cells in vitro. Method A series of 10-fold dilutions of XE-TNFαm2, SIVmac251 and CEMx -174 cells were cultured at 37癈 for 5 days. Anti-SIV activity was detected with P27 Enzyme-Linked Immunosorbent Assay (ELISA). The percentage of apoptosis was analyzed by flow cytometry. Result XE-TNFαm2 had low cytotoxicity to CEMx -174 cells，and could inhibit the cell infection of SIV. The highest percentage of inhibition was 40%. Conclusion Our results demonstrate that XE-TNFαm2 could inhibit SIV infection and conduct apoptosis on infected cells.