Abstract: In this study, the chicken Mx promoter（Mxp）was cloned, and luciferase (luc) gene was inserted into downstream of Mxp. Then pMxp-luc was constructed for the bioactivity assay of type Ⅰ IFN and the assay was developed and described as follows. Chicken embryo fibroblast cell line (DF-1) was transfected with pMxp-luc. 24 h later, the cells were incubated with 10-fold diluted chicken IFN-α and IFN-β for another 6 h. The expression of luciferase was stimulated by Mxp and had a good linear correlation with the antiviral activity of IFN. This new method was 10- and 100-fold more sensitive than the antiviral assay to quantify chicken IFN-α and IFN-β, respectively. In conclusion, the reporter gene assay described here is more rapid, safe and accurate than antiviral assay, and has potential value for high-flux assay and great value in the fundamental and application study of avian and mammalian type Ⅰ IFN.