With the horseradish peroxidase histochemical technique and electron microscope, the effects of 0.5% timolol, Inj. Salviae Miltiorrhizae Co. and their combination on the retrograde axoplasmic transport in the optic nerve of 230 rabbit models of chronic IOP elevation were studied. The results showed that (1) the nerve damage in chronic glaucoma was due to multiple factors; (2) the use of a drug that improved microcirculation in combination with an IOP depressor better protected the optic nerve functions than did the latter alone; and (3) Inj. Salviae Miltiorrhizae Co. improved the optic nerve axoplasmic transport under chronic IOP elevation. The mechanism of the drug in protecting the optic nerve could be through its actions of improving the local microcirculation and the tolerance of nerve tissues to anoxia.