In order to study explosion pressure load distribution characteristics in closed environment, a TNT charge internal explosion experiment of cylinder apparatus with an aspect ratio of 2∶1 was carried out. Pressure load data of the cylinder wall and cover plate were obtained, and the pressure load characteristics and distribution laws of the wall and cover plate were analyzed combining the simulation results. The model of peak pressure load was established and validated. The results show that the pressure load waveforms of the cylinder wall and cover plate are not exactly identical, and the cylinder wall pressure load changes from obvious single wave peak to multiple peak values as the distance to explosion center increasing. The attenuation characteristics of pressure load in the near-field area were similar to that of a free ground blast wave with certain explosion height. The pressure load of the cover plate shows a characteristic of multiple wave peaks, of which, the maximum peak of the pressure load in the central area is 3 times larger than the first peak value, and the corner part is 6 times larger than the first peak value. The maximum peak of the pressure load on the cylinder wall shows a concave distribution. The results of this study can provide reference for the analysis of the internal explosion pressure load and evaluation of the structure damage.