Abstract: OBJECTIVE To study the effect of Gualou Guizhi granule on the calcium signal pathway in N-methyl-D-aspartic acid(NMDA)-induced neuronal excitability toxicity, intend to illustrate its possible mechanism. METHODS The excitotoxicity damage model of neurons induced by NMDA was established. The activity of neuron was detected by MTT and LDH, and the expression of MAP-2 protein was detected by immunofluorescence staining after administering with the Gualou Guizhi granule. Real-time PCR was used to detect the expression of CaMKⅡ and CREB in neurons. And the expression of p-CREB, p-CaMKⅡ, CaMKⅡ, CREB and CaM protein were detected by Western blot. RESULTS Compared with NMDA group, Gualou Guizhi granule (200,300 μg·mL^-1) group significantly increased cell viability and decreased LDH concentration (P<0.05 or P<0.01), significantly increased the mRNA levels of CREB and CaMKⅡ(P<0.05 or P<0.01), significantly increased the levels of MAP-2, p-CREB, p-CaMKⅡ and CREB(P<0.01), and significantly decreased CaM level(P<0.01). CONCLUSION Gualou Guizhi granule have protective effect on the excitotoxicity damage induced by NMDA, which may be related to the phosphorylation of CREB and CaMKⅡ and the inhibition of the expression of CaM.