In order to study the change law of the dielectric constant of coal rock under different conditions, this paper establishes an experimental system of the dielectric constant of coal rock containing gas, and tests and analyzes the change law of the dielectric constant of coal rock in the process of gas desorption under different gas pressure and bedding direction. The results show that the bedding direction has a significant effect on the dielectric constant of coal rock. After the gas adsorption equilibrium, the dielectric constant of vertical bedding coal rock is much higher than that of parallel bedding coal rock. During the desorption process, the dielectric constant of vertical bedding coal rock shows an upward trend as a whole, while the dielectric constant of parallel bedding coal rock shows a downward trend as a whole. With the decrease of gas pressure, the change of dielectric constant is more obvious. This study systematically expounds the mechanism of gas pressure and bedding direction on the dielectric constant of coal rock, and provides experimental basis for the prediction of coal rock dynamic disaster by electrical exploration technology.