Objective：To investigate whether Del-1 is expressed in human periodontal ligament cells（hPDLCs），and the effect of lipopolysaccharides（LPS）on the expression of Del-1 in hPDLCs，and to explore the potential mechanism of Del-1 in the development of periodontitis. Methods：HPDLCs were isolated and cultured by tissue block method，and immunofluorescence assay，flow cytometry and Matrigel assay were used to identify cells. Immunofluorescence was used to detect if Del-1 was expressed in hPDLCs. Then variable concentrations of LPS were used to stimulate hPDLCs，and the expression of Del-1 was detected. The optimal concentration of LPS was selected，based on the most significant decrease of Del-1. The optimal concentration was selected to be used in the time-dependent experiment. The expressions of Del-1 and IL-6 were respectively assayed. hPDLCs were pretreated with Del-1 of variable concentrations（0，0.05，0.5 and 5 μg/mL）for 1 h，and then stimulated with LPS for 24 h. The expressions of IL-6 were assayed. hPDLCs were pretreated with the optimal concentration of Del-1 for 1 h，and then stimulated with LPS for 10 min，for detecting the phosphorylation of IκBα. Results：Del-1 could be expressed in hPDLCs，locating in cytoplasm of hPDLCs. The expressions of Del-1 were significantly down-regulated by LPS in a dose-independent and time-independent manner，which were contrary to IL-6. Del-1 could down-regulate the expression of IL-6 which was induced by LPS and inhibit the phosphorylation of IκBα in hPDLCs. Conclusions：Our study discovered for the first time that Del-1 could be expressed in hPDLCs，and it was down-regulated by LPS in hPDLCs，Del-1 could suppress the phosphorylation of NF-κB，playing an antagonistic role in the development of periodontitis.