Abstract: The relationship between coal gas content and coal gas pressure was studied, based on the studied on coal gas pressure produce mechanics and the coal gas reservoir. The coal gas content and coal gas pressure can be calculated by Langmuir Equation, when the seam keeps full integrity. Otherwise, when the coal seam keeps the condition of dispersion and composes of massive, although it exists gas content in coal seam, the relation between coal gas content and coal gas pressure is not fit Langmuir Equation.