In order to investigate whether there exists LMP1/JAK3/ STAT signal pathway in NPC cell line, RT-PCR was first used to detect that four of JAK family members all expressed in two NPC cell lines CNE1 and HNE2. JAK3 which is the most possible associated with LMP1 was used to study further. A stable cell line Tet-on-LMP1 HNE2 expressing LMP1 regulated by tetracycline derivative Dox was used as a model. Western blotting was used to detect JAK3 expression in dose and time dependent fashion under dynamic changes of LMP1. STAT activity was observed after STAT reporter gene GRR-luc was transient transfected in Tet-on-LMP1 HNE2 cell and was induced by varied Dox dose for 36 h. At Dox concentration of 0.06 mg/L, STAT activity reached a peak. JAK3 specific inhibitorⅠ WHI-P131 can inhibit this peak STAT activity at concentration of 3 μmol/L. Therefore, JAK3 expressed in NPC cells can be regulated by LMP1 to activate STAT. The identified LMP1/JAK3/STAT signal pathway maybe plays an important role in NPC carcinogenesis.