Abstract: Objective To produce recombinant TpN17 Treponema pallidum antigen with genetic engineering technique and establish simple indirect enzyme-linked immunosorbent assay(ELISA) with high sensitivity and specificity for detecting syphilis antibodies in serum. Methods The TpN17 gene was amplified from TP genome by PCR. Amplification fragments of the target genes were sequenced after T-A cloning and cloned into prokaryotic expression vector to express recombinant TpN17 protein, The recombinant fusion antigen was purified with affinity chromatography. Based on this recombinant fusion antigen, one kind of indirect enzyme-linked immunosorbent assay(ELISA) was established. Then, the serum samples were tested by this method, and its results were compared with the same samples detected by treponema pallidum hemagglutination assay（TPHA） and toluidine red unheat serum test（TRUST）. Results TpN17 protein was highly expressed in E.coli BL21,and an indirect enzyme-linked immunosorbent assay(ELISA) was established successfully. The results from 135 suspected serum samples of syphilis showed that the positive rates detected by ELISA、TPHA and TRUST were 82.96%、98.52% and 71.11%, However,among 8 suspected sera and 31 negative sera by TRUST,39 were positive according to TPHA, only 2 were negative according to ELISA. Conclusion According to the sensitivity and specificity, ELISA to the recombinant fusion TpN17 antigen is obviously superior to TRUST.