Dysthyroid optic neuropathy (DON) is the most serious complication of Thyroid-Associated Ophthalmopathy(TAO). Untimely and ineffective treatment of could lead to permanent blindness. Early detection is the principle factor for timely intervention. Diffusion tensor imaging(DTI) is a noninvasive tool to reveal microstructural or non-overt damage and quantify pathological processes of nerve fiber bundle. We applied the multi-parametric of optic nerve to identify the DON from TAO. The result reveals that DTI can be considered a useful and noninvasive tool to differentiate DON from TAO with higher accuracy.