Cisplatin is an effective chemotherapeutic agent against many common types of cancers. However, one of its most severe and debilitating side effects is ototoxicity. The purpose of this study was to investigate the mechanisms of laminarin protective effects on cisplatin-induced damage in HEI-OC1 auditory cell line. In our research, HEI-OC1 cells were pretreated with laminarin and then exposed to cisplatin. Here, we examined the cell viability, cell apoptosis and the factors associated with apoptotic pathway. Compared with cisplatin injured group, pretreatment with laminarin increased cell viability and decreased the cell apoptosis and necrosis. Furthermore, treatment with laminarin reduced intracellular ROS production, bax mRNA, and cleaved caspase-3, caspase-9, caspase-8 expression, but increased the bcl-2 mRNA level. The protection was ascribed to the radical scavenging activity of laminarin, and the inhibition of both mitochondrial apoptosis pathway and extrinsic apoptotic pathway.