To explore the antimicrobial mechanism of human cervical mucus, HCP-21and HCP-26 were isolated and purified from acid-soluble extracts of human cervical mucus by acid-urea polyacrylamide gel electrophoresis and reversed-phase high-performance liquid chromatography(RP-HPLC). Both molecules could effectively kill E. coli ML-35p determined by agarose radial diffusion assay. The N-terminal amino acid sequence of HCP-21 was PKRKAEGDAK and its molecular mass was 9 263.62 identified by amino acid sequencing and mass spectrometry analysis. HCP-21 showed 100% identity to HMGN2 (high mobility group protein N2, HMGN2) fragment 2～11 by GenBank BLAST searching, and had the same molecular mass as HMGN2. So it was certain that HCP-21 was HMGN2. HCP-26 was SLPI (secretory leukocyte protease inhibitor, SLPI) fragment by N-terminal amino acid sequencing which was SGKSFKAGVC. It was the same with SLPI fragment 26～35 by GenBank BLAST searching. Total RNA was extracted from primary culture cervical epithelial cells, and the specific primer was designed based on HMGN2 cDNA sequence. RT-PCR showed that a fragment about 270 bp was amplified, which was same to HMGN2 cDNA. It was suggested that cervical epithelial cells could express HMGN2 mRNA in physiological condition. The fusion protein GST-HMGN2 was purified by low-pressure chromatography. The antiserum of HMGN2 was prepared from the immune rabbit with the fusion protein. Cervical tissue paraffin section and cervical mucus smear were detected by immunhistochemistry. The staining results showed that HMGN2 mainly distributed in mucosa surface of cervix and existed in cervical mucus. HMGN2 constitutively expressed in cervical mucosa and mucus, so it might play an important role in innate defensive of cervical.