Objective:To construct luciferase reporter plasmids of full-length and truncated promotors of rat X-linked inhibitor of apoptosis associated factor 1(XAF1) gene and detect their activity in HEK293 cells in response to interferon regulatory factor-1 (IRF-1) overexpression,screening the possible binding sites for IRF-1. Methods: Rat XAF1 promoter(-1497 ~ +166 nt) was amplified by PCR and cloned into the luciferase reporter plasmid(pGL3-basic). The recombinant plasmid(pGL3-XAF1-QC) and rat IRF-1 expression plasmid(pcDNA3.1-IRF-1) were co-transfected into HEK293 cells and then the luciferase activity was detected to comfirm the role of IRF-1 in XAF1 gene transcription. Meanwhile,the possible IRF-1 binding sites within XAF1 promoter were predicted by using bioinformatics software. Based on the predicted results,different luciferase reporter plasmids of truncated XAF1 gene promotor (pGL3-XAF1-1,pGL3-XAF1-2,pGL3-XAF1-3 and pGL3-XAF1-4) were constructed. The promoter luciferase reporter plasmids of pGL3-XAF1-QC or pGL3-XAF1-1,-2,-3,-4 and the plasmid of pcDNA3.1-IRF-1 were co-transfected into HEK293 cells. Then,the luciferase activity was detected to screen the IRF-1 binding sites. Results: It was verified that different kinds of plasmids were all constructed correctly by PCR analysis and nucleotide sequencing. The plasmids of pGL3-XAF1-QC and pcDNA3.1-IRF-1 were co-transfected into HEK293 cells,and then the luciferase activity was detected. The result showed that the transcriptional activity of XAF1 gene was increased markedly in response to IRF-1 overexpression. In addition,when the plasmids of pGL3-XAF1-QC or pGL3-XAF1-1,-2,-3,-4 and pcDNA3.1-IRF-1 were co-transfected into HEK293 cells,the activity of pGL3-XAF1-3 was much lower than that in pGL3-XAF1-1 and pGL3-XAF1-2,indicating that the region of rat XAF promoter(-337 ~ -47 nt) might contain IRF-1 binding element. Conclusion: The rat full-length and truncated rat XAF1 promotor luciferase reporter plasmids were constructed successfully,and the IRF-1 binding region was found,which could be beneficial to further studies.