Speech is a basic and natural form of human communication. However, people with speech disorders have always have great difficulties in communicating. Research on speech neural decoding is more conducive to helping patients with speech disorders communicate with the outside world. As an emerging speech method, imagined speech only requires the subjects to make the sound of the corresponding material in their hearts. Since the perception and production of language originate from specific areas of the cerebral cortex, the brain activity between imagined speech and overt speech is similar, but its internal neural mechanism is not yet fully understood. This study designed a specific imagined speech experimental paradigm, collected and analyzed the electroencephalogram data corresponding to imagined speech, and revealed the time domain, rhythm, time-frequency and neural responses of specific brain areas during the production and processing of imagined speech, which provided theoretical support for imagined speech neural decoding, promoted the development of speech-assisted communication brain-computer interface system, helped patients with speech disorders communicate with the outside world, and truly improved the quality of life of patients with speech disorders.