Penthorum chinense Pursh (P. chinense), a traditional Chinese medicine used by the Chinese Miao minority, has been used to treat liver diseases for a long time. However, the mechanism behind the liver protective effects of P. chinense remains unclear so far. The aim of the present study was to investigate the hepatoprotective effect of P. chinense and its possible mechanism(s). Immortalized normal human normal liver L02 cells were used to evaluate the protective effect of P. chinense aqueous extract against tert-butyl hydroperoxide (t-BHP)-induced liver cell damage. Treatment with P. chinense aqueous extract significantly protected L02 cells from t-BHP-induced cytotoxicity, prevented t-BHP-induced reactive oxygen species (ROS) generation and decreased the percentage of apoptosis by inhibiting the mitochondrial apoptotic pathway. This study demonstrates that P. chinense is a potential hepatoprotective agent in t-BHP-induced liver cell damage, which may benefit the further application of P. chinense in the clinic. © 2015 by the authors; licensee MDPI.