During the period of 1875, British surgeon Caton recorded the current directly in the exposed brain of animals, and inserted the electrode directly into the skull of the monkey head to detect the current activity in the brain. 1903, inspired by these achievements, German medical scientist Berger began the experiment of recording brain current: firstly, the exposed brain of dogs was tested, then needle electrodes were inserted under the scalp to provide patients with the opportunity of skull resection, and finally the whole skull function of normal people and brain patients was tested and succeeded. He named the method of recording human EEG as EEG, which became the beginning of clinical application of EEG. 1929 published an important scientific paper on human EEG, pointing out that EEG may become a new subject in the diagnosis of encephalopathy and neurophysiology. Since the 1940s, it has been widely used in clinical diagnosis. 1934, Adrian and Matthews improved the EEG, so that it can diagnose some types of epilepsy, insanity and brain tumors, as well as detect intracranial lesions and locate brain lesions. 1950, Boze and Shuboveri began to apply EEG. At present, this examination is mainly used for the auxiliary diagnosis of cerebrovascular diseases. In 1930s, the recording method of EEG was mainly recorded by oscillographic photography after being amplified by electron tube amplifier. By 1950s, computer technology was introduced into the field of EEG. After 1970s, integrated circuits and * * * mode suppression technology were used to discharge EEG signals, and tape recorders were used to record EEG signals, which not only further reduced the volume of EEG, but also greatly improved its anti-interference performance.