Objective: To investigate the effects of salvianolic acid B (Sal B) on the quality of stored red blood cells (RBC) and to preliminarily explore its underlying mechanisms. Methods: Whole blood was collected from healthy adult volunteers, and suspended RBC were prepared and stored in MAP (mannitol-adenine-phosphate) solution. The RBC suspensions were divided into a control group and a Sal B group, with the latter supplemented with Sal B at a final concentration of 10 μM. All samples were mixed and stored at 2-6℃. RBC were collected on days 0, 7, 14, 21, 28, and 35 for evaluation. RBC damage was assessed through cell counting, morphological observation, osmotic fragility test, and hemolysis rate measurement. Cytosolic ROS levels and intracellular SOD activity were measured to evaluate oxidative stress. Results: Sal B helped maintain RBC morphology and osmotic stability, and reduced the generation of morphologically abnormal cells such as spherocytes and echinocytes. On days 28 and 35, the hemolysis rate in the Sal B group was significantly lower than that in the control group. Compared with the control group, the Sal B group exhibited decreased cytosolic ROS levels and increased intracellular SOD activity from day 14 onward. Conclusion: Sal B alleviates RBC storage lesion by reducing oxidative stress.