Electroencephalogram (EEG) is the electrical potential changes that occur in the cerebral cortex, as  the response of the discharge of nerve cells in the brain, and can reflect the feature of the electrical  activity of the brain. From the discovery of EEG in 1929 to the present, it has been extensively  studied by scholars from all over the world. Nowadays, the research of EEG continues to deepen,  and the scope of application is gradually extensive, such as clinical application, medical teaching  and scientific research. EEG Source Imaging (ESI), which through the collection and processing  of EEG to identify brain activity information, can be used to assist the diagnosis and treatment of  epilepsy, depression, attention deficit hyperactivity disorder and other diseases. ESI has attracted  much attention in the brain research, which is commendable in improving the clinical diagnosis  ability of brain physiological diseases and other diseases. This paper introduces the basic principle  and research status of ESI briefly, focuses on the positive and inverse problems of EEG, analyzes  three important factors affecting the positioning accuracy of ESI, analyzes the existing problems and  development prospects of ESI in the end. The purpose of this paper is provide a solid theoretical basis  for continuously improving the positioning accuracy of ESI technology, more accurately locating  abnormal brain function areas, and further understanding and treating brain diseases by studying  the source imaging technology based on brain electricity.