Abstract: The dielectric constant of coal is an important parameter to study the propagation characteristics of electromagnetic wave in coal, in order to analyze the propagation of electromagnetic wave in coal better, improve and develop the existing technology and the theory of coal dielectric physics, based on the domestic and foreign literature research, this paper systematically analyzed and summarized the research status of the influencing factors of coal dielectric constant, discussed the variation of the coal dielectric constant with coal rank, moisture, mineral and test frequency, pointed out the deficiency of the research methods of the influencing factors of the coal dielectric constant and the new development direction of preventing the coal mine water disaster and fire. The results showed that there were many factors affecting the dielectric constant of coal. They were usually divided into major factors and minor factors. Under certain conditions, they could be changed dynamically or transformed.