Objective To investigate the inhibitory effect of gallic acid (GA) on lipopolysaccharide ( LPS)- induced inflammatory responses in human THP1 macrophages. Methods THP1 monocytes were differentiated into macrophages with phorbol myristate acetate. A macrophage inflammation model was established with LPS induction, and GA was added at different concentrations. The safe concentrations of LPS and GA for THP1 cells were screened using the CCK-8 method, and a normal group, model group ( 100 μg / L LPS), and GA group ( 100 μg / L LPS + different concentrations of GA) were set up. ELISA was used to detect the levels of interleukin ( IL)-6, tumor necrosis factor-α (TNF-α), and IL-1β in the cell culture media of each group. The microplate method was used to detect lactate dehydrogenase ( LDH) activity and NO content in the cell cultures, and fluorescence staining was used to detect the reactive oxygen species (ROS) levels, cell damage, and changes in mitochondrial transmembrane potential in each group.Western blot was performed to detect the levels of cyclooxygenase-2 ( COX-2), HMGB1, c-Jun amino-terminal kinase(JNK), extracellular-regulated protein kinase (ERK), P38 mitogen-activated protein kinase (P38), nuclear transcription factor-κB (NF-κB), NOD-like receptor protein 3 (NLRP3), Caspase-1, IL-1β, and gasdermin D (GSDMD). Results Compared with the normal group, the model cell group’ s secretion of IL-6, TNF-α, IL-1β, and NO was increased (P<0. 05); the secretion of COX-2, HMGB1, p-ERK, p-JNK, and p-P38 and expression of p-NF-κB, NLRP3, Caspase-1,IL-1β were elevated ( P<0. 05); expression of GSDMD protein activation fragment was reduced ( P<0. 05); ROS generation and cellular damage were significantly increased; mitochondrial transmembrane potential was significantly lower;and LDH activity was elevated (P<0. 05). In comparison with the model group, the GA group cells’ secretion of IL-6,TNF-α, IL-1β, and NO was decreased (P<0. 05); expression of COX-2, HMGB1, p-ERK, p-JNK, p-P38, p-NF-κB,NLRP3, Caspase-1, and IL-1β was decreased ( P<0. 05); GSDMD protein activation fragment expression level was increased ( P<0. 05); ROS generation and cellular damage were decreased; mitochondrial transmembrane potential gradually increased; and LDH activity was decreased (P<0. 05). Conclusions GA had an inhibitory effect on the LPSinduced inflammatory response in THP1 macrophages, and its anti-inflammatory mechanism may involve the MAPK and NF-κB signaling pathways.