Objective: To study the antibacterial activity and stability of Polygonum chinense Linn extracts against standard strains of Staphylococcus aureus in vitro. Methods: The antibacterial activity of Polygonum chinense Linn extracts on the Staphylococcus aureus were determined by oxford cup test and microdilution broth method. The OD_{600 nm} value of S. aureus was used as an index, and the influence of pH, temperature, ultraviolet radiation and metal ions on its stability was explored. Results: The results showed that Polygonum chinense Linn extracts had certain inhibitory activity on Staphylococcus aureus, and the minimum inhibitory concentration was 8 mg/mL. In addition, Polygonum chinense Linn extracts had good antibacterial stability in the presence of heat treatment, acidic and basic condition, ultraviolet irradiation, but it was sensitive to metal ions. The antibacterial effect of metal ions on the Polygonum chinense Linn extracts was different,0.1 mol/L Na⁺ and K⁺ could reduce its antibacterial effect, but under the treatment of 0.1 mol/L Ca²⁺, the antibacterial activity was lost. Conclusion: Polygonum chinense Linn extracts had stable inhibitory activity against S. aureus in vitro.