Objective: To explore the expressions of IL-1β and COX-2 in the gingiva tissues in rat periodontitis model with different estrogen levels, and the effect of estrogen level on periodontitis. Methods: A total of 40 female Wistar rats were randomized into 4 groups, i.e. normal control group (n=10), periodontitis group (n=10), castraction periodontitis group (n=10), and estrogen therapy group (n=10). RT-PCR was used to detect the expressions of IL-1β and COX-2 in the gingiva tissues in each group. Results: The expression intensity of IL-1β and COX-2 in the estrogen therapy group was significantly lower than that in the castraction periodontitis group (P<0.05). Conclusions: Estrogen can significantly down regulate the expressions of IL-1β and COX-2 in order to alleviate the symptoms of periodontitis.