Abstract: OBJECTIVE To report the analysis and treatment of liver function injury caused by heparin sodium injection in the positive control group in an early clinical study of new drugs, in order to provide reference for the clinical use of heparin sodium injection and provide ideas for the treatment of adverse reactions. METHODS Analyzed and summarized one case of liver injury in a tolerance and pharmacokinetics study of a new anticoagulant drug with both placebo and heparin sodium as control, described the case process, analyzed the cause, and discussed the enlightenment for treatment of adverse event in early clinical research and the safety of heparin sodium in clinical use. RESULTS Three cases occurred different degrees increasing of alanine aminotransferase and aspartate aminotransferase after 4 healthy subjects were infused with heparin sodium for 5 consecutive days. It was considered that those were adverse reactions caused by heparin sodium. Timely treatment was performed by strengthening monitoring and administrating liver protective drugs. Protocol was revised to avoid further injury to the follow-up subjects. CONCLUSION Continuous infusion of heparin sodium injection can easily cause liver function damage, and should be given sufficient attention during clinical use. Early clinical research should promptly analyze and handle adverse reactions to ensure the safety of subjects.