Abstract: OBJECTIVE To select the best pH value for bacteriostasis through studying of different pH values of Qiangli Pipa Syrup, which provide the basis for the large-scale production of prescription technology. METHODS The quality of adjusting different pH values with citric acid dosage was compared by methods of antibacterial effect, content detection, and fingerprinting, etc. RESULTS The pH value of Qiangli Pipa Syrup was adjusted to about 4.10 by 3.17 g citric acid per prescription, its antibacterial effect was significantly improved, the growth and reproduction and gas production of microorganisms were effectively inhibited. There was no significant difference in product content, fingerprint, and other quality indicators. CONCLUSION The optimized process is reasonable and feasible, the product quality is stable, and the established fingerprint quality control method has strong specificity and good repeatability.