Abstract: Rabdosia japonica(Burm.f.) Hara var.glaucocalyx(Maxim.) Hara is a traditional Chinese medicine, and is known to have anti-tumor effects. This study aims to investigate the effect of glaucocalyxin A (GLA), a diterpenoids extracted from Glaucocalyx Hara, on apoptosis of glioma cells and its mechanism. This study investigated the molecular signaling mechanism of GLA-induced glioma cell apoptosis by analyzing survival rate of C6 rat glioma cells, cell morphology, colony formation ability, interference ribonucleic acid, polymerase chain reaction, and Western blot. The result showed that in the presentce of GLA, the survival rate of C6 rat glioma cells decreased significantly, while the expression of guanine nucleotide-exchange factor-H1 was up-regulated, causing phosphorylation of extracellular regulated protein kinases proteins and apoptosis. Hence, the mechanism of GLA-induced glioma cell apoptosis was the GEF-H1/ERK pathway.