Gingivitis is an inflammatory disease that affects gingival tissues through a microbe-immune interaction. Huanglian Jiedu decoction (HLJD) is used traditionally for clearing and detoxifying in China, which had been reported to possess many pharmacological effects. Rat gingival inflammation model was established by lipopolysaccharide (LPS) injection for 3 consecutive days, and HLJD was given by gavage before LPS injection. After 3 days rats were sacrificed and tissue samples were evaluated. Serum cytokine levels such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were measured by enzyme-linked immunoabsorbent assay (ELISA). Oxidative stress related molecules such as total antioxidant capacity (T-AOC), malondialdehyde (MDA), and reactive oxygen species (ROS) were determined. Expression of AMP-activated protein kinase (AMPK) and extracellular signal-regulated kinases 1/2 (ERK1/2) signaling pathway were inspected by western blotting. Histological changes of gingival tissues were tested with hematoxylin-eosin (HE) staining. HLJD significantly decreased serum levels of IL-6 and TNF-α, suppressed generation of MDA and ROS, and enhanced T-AOC creation. Moreover, HLJD inhibited expressions of AMPK and ERK1/2. The inflammation severity of gingival tissue by HE staining was severe in model group but relieved in HLJD group obviously. HLJD exhibited protective effects against gingival damage through suppressing inflammation reaction and elevating antioxidation power.