An UPLC method was developed to evaluate the quality of Paeoniae Radix by simultaneously determining four components, paeoniflorin, albiflorin, benzoylpaeoniflorin and paeonol in Paeoniae Radix Alba decoction pieces. The UPLC chromatographic column was ACQUITY UPLC® HSS T3. The mobile phase was acetonitrile-0.05% phosphoric acid water with gradient elution. The column temperature was 30 °C and detection wavelength was 230 nm with a flow rate of 0.4 mL · min(-1). A linear model was obtained through principal component analysis (PCA), and PCA scores were used to evaluate the quality of Radix Paeoniae Alba decoction pieces comprehensively. Paeoniflorin, albiflorin, benzoylpaeoniflorin and paeonol could be well separated from other components, and the results of specificity, precision, repeatability, linearity, recovery rate and stability reached the standards, respectively. The content of paeoniflorin in 9 batches of Paeoniae Radix Alba decoction pieces was below the standard given by Chinese Pharmacopoeia (2010 edition). Using the comprehensive scoring method with principal component analysis, the results showed that the samples from Zhejiang province have better quality than those from Anhui and Shandong provinces. The method established in this study can effectively determine the content of paeoniflorin, albiflorin, benzoylpaeoniflorin and paeonol, which could be used for quality control of Paeoniae Radix Alba.