AIM:To investigate the the protective effect of MK-801 on retinal ganglial cells（ RGC ) of SD rats with chronic ocular hypertension. METHODS:To prepare chronic ocular hypertension model of SD rats，36 SD rats were randomly divided into 3 groups： blank control group，chronic elevated intraocular pressure + saline control group，chronic elevated intraocular pressure + MK-801 treatment group (n=12). The glutamate acid content, retinal thickness and the inner layer thickness，number of retinal ganglion cell,retinal ganglion cell apoptosis of each group were observed and compared at different time points ( 1day, 4, 7and 10days after treatment) . RESULTS:Retinal glutamate acid levels increased (P<005) in SD rats with chronic elevated intraocular pressure and those in MK-801 treatment group were significantly lower than the same period in normal saline control group (P<0.05). HE staining showed that retinal thickness and the inner layer thickness of MK-801 treatment group and blank control group were greater than the saline control group (P<0.05), the numbers of RGC were higher than the saline control group (P<0.05). The positive expression of apoptotic RGC in MK-801 treated group were less than the saline control group.  CONCLUSION:MK-801 could protect the RGC of chronic elevated intraocular pressure by blocking the glutamate-mediated neurotoxicity.