Eye tracking technology is an effective method to study cognitive behavior and its neurophysiological mechanisms. Combined with cognitive tasks, eye tracking technology enables the quantification and process measurement of the brain's cognitive functions. It has better temporal resolution and sensitivity compared with traditional neuropsychological scales, and it gets higher repeatability by reducing the interference of human factors. In this review, we trace the development of eye tracking technology and its current application in cognitive assessment of neurological diseases, discuss the eye tracking characteristics in different neurological disorders and cognitive impairments, and outline the prospect of eye tracking technology in cognitive assessment.