Abstract: In order to investigate the influence of pore pressure and temperature on the permeability of coal rocks, based on the constant effective stress, the experiment of coal rock permeability at different pore pressures and temperatures are carried out with the self-developed coal permeability experiment device. It shows that under constant effective stress conditions, coal rock permeability has a negative power exponential relationship with pore pressure and temperature. With the increase of pore pressure or temperature, the permeability shows a similar change law, which first decreases rapidly and then tends to gently. The critical values of the test coal rock pore pressure and temperature on coal rock nitrogen permeability are obtained; and the relationship between permeability and temperature and pore pressure was obtained.