〔Abstract〕 Objective Long-term stability test was used to investigate the storage stability of Rhizoma Alismatis decoction pieces and the evaluation indexes of rhizoma alismatis in the room temperature warehouse and shady warehouse laying the foundation for the storage management standard of rhizoma alismatis decoction pieces. Methods The relevant methods in "Chinese Pharmacopoeia" were used to detect the water and extract of rhizoma alismatis. Ultra Performance Liquid Chromatography (UPLC) method determination rhizoma alismatis decoction pieces (rhizoma alismatis decoction pieces and rhizoma alismatis salt decoction pieces) mesoepoxyalisene, 23-acetyl alismatid alismatid C, alisma alcohol A, alismenol, alismatis alcohol B, 23-acetyl alismatol B, 11-deoxygenated alismatol B, the amount of seven ingredients, chromatographic column: Thermo Fisher Scientific Syncronis aQ chromatographic column (100 mm×2.1 mm, 1.7 μm) with mobile phase consisted of acetonitrile (A)-water (B) and gradient elution (0-0.2 min, 35% → 35% B; 0.2-2.5 min, 35 %→55 % B; 2.5-3.5 min, 55 %→55 % B; 3.5-6.5 min, 55 %→3 % B; 6.5-9.5 min, 73 %→87 % B; 9.5-14 min, 87% → 87% B). The flow rate was 0.25 mL·min-1, the injection volume was 5 μL, the column temperature was 35 °C, and the detection wavelength was 208 nm. Results The contents of water, extract and 7 components of rhizoma alismatis decoction pieces in normal temperature storehouse and cool storehouse did not change significantly. All batches of decoction pieces were free from moths and mildew within 12 months of storage, and all indexes were in line with the requirements of "Chinese Pharmacopoeia" in the long-term 12-month stability study time, and the quality of rhizoma alismatis decoction pieces was stable. Conclusion Rhizoma alismatis decoction pieces can be stored at room temperature for up to 12 months. This study provides experimental reference for standardized and appropriate storage of Rhizoma Alismatis decoction pieces.