Chronic atrophic gastritis (CAG) is the precancerous stage of gastric carcinoma. Traditional Chinese Medicine (TCM) has been widely used in treating CAG. This study aimed to reveal core pathogenesis of CAG by validating the TCM syndrome patterns and provide evidence for optimization of treatment strategies. This is a cross-sectional study conducted in 4 hospitals in China. Hierarchical clustering analysis (HCA) and complex system entropy clustering analysis (CSECA) were performed, respectively, to achieve syndrome pattern validation. Based on HCA, 15 common factors were assigned to 6 syndrome patterns: liver depression and spleen deficiency and blood stasis in the stomach collateral, internal harassment of phlegm-heat and blood stasis in the stomach collateral, phlegm-turbidity internal obstruction, spleen deficiency, internal harassment of phlegm-heat and spleen deficiency, and spleen deficiency. By CSECA, 22 common factors were assigned to 7 syndrome patterns: deficiency, stagnation, blood stasis, phlegm turbidity, heat, deficiency, and deficiency. Combination of deficiency, stagnation, blood stasis, phlegm turbidity, heat, deficiency, and deficiency play a crucial role in CAG pathogenesis. In accord with this, treatment strategies by TCM herbal prescriptions should be targeted to regulating , activating blood, resolving turbidity, clearing heat, removing toxin, nourishing , and warming . Further explorations are needed to verify and expand the current conclusions.