Event-related potential(ERP) is a series of brain waves formed by the brain response with fixed time relationship with actual stimulus or expected stimulus. The ERP component can be extracted by using the fixed stimulus response lock time relation and the computer's average superposition processing. Because the endogenous components of ERP are closely related to cognitive processes, they are also known as cognitive potentials. With the increase of age, the speed of brain function decline is accelerating. With the prolongation of the average life span of human beings, we will enter the aging society. Following that is the increase of brain dysfunction and the prevalence of dementia. How to determine the status of cognitive function and provide accurate information for clinical diagnosis and treatment evaluation has become an important issue. The emergence of event related potential (ERP) and its clinical application provide a technical platform for this purpose.