In recent years, there has been an increase in the incidence of herbal-induced liver injury due to the accidental ingestion of herbal medicines containing pyrrolizidine alkaloids (PAs) in domestic. Salvianolic acid B (Sal B), a hydrophilic component in Salvia miltiorrhiza Bge., shows activities of anticoagulation, antioxidation, and other pharmacological activities. This research aims to investigate the protective effect of Sal B on hepatotoxicity induced by senecionine (SEN) and its potential mechanism. The animal experiment was approved by the Experimental Animal Ethical Committee of Shanghai University of Traditional Chinese Medicine, and all mice have received humane care in compliance with the institutional animal care guidelines. Mice were treated with Sal B (10 mg·kg^-1) 3 days before and 1 day after SEN (50 mg·kg^-1) treatment. The animals were sacrificed 48 h after SEN administration. As a result, Sal B effectively ameliorated SEN-induced liver injury. The mice in the group treated with Sal B showed lower serum activities of alanine aminotransferase and aspartate aminotransferase, less hepatic sinusoidal hemorrhage, and reduced hepatocyte necrosis. Besides, contents of pyrrole-protein adducts, the marker for PA-induced toxicity, were also decreased in serum. The key factors related to coagulation, oxidative stress, and liver fibrosis were further analyzed. It was found that Sal B inhibited the coagulant system by reducing the expression of plasminogen activator inhibitor-1. Sal B also modulated glutathione and superoxide dismutase levels and improved the anti-oxidative defense system. In addition, Sal B decreased the excessive deposition of extracellular matrix and inhibited the progression of liver fibrosis via down-regulating several key factors related to liver fibrosis, including matrix metalloproteinase 9, transforming growth factor-β1, signal transducer and activator of transcription 3, and chemokine 1. In conclusion, Sal B ameliorated SEN-induced liver injury in mice by regulating the blood coagulation system, improving oxidative stress, and modulating liver fibrosis-related factors. Our present study pointed to the possibility of utilizing salvianolic acid B for protection against PA-induced liver injury clinically.