Abstract: The maximum explosion pressure and maximum explosion pressure rate produced by different filling ratios in the flameproof chamber are different. In order to study the change characteristics of gas explosion under different filling ratios in flameproof chamber, the flameproof enclosure with a flameproof chamber size of 750 mm×750 mm×600 mm is used as the test container, and 5 pressure sensors are arranged on the two walls of the chamber respectively. The experiment was carried out under the conditions of filling ratio of 0, 10%, 20%, 30%, 40%, 50%, 60%, 70% and 80% respectively. The characteristic parameters of explosion pressure and pressure rise rate in flameproof cavity were obtained. The results show that in the flameproof chamber, the peak value of explosion pressure in the cavity state is the largest, and the maximum value appears at the PRU pressure measurement point farthest from the ignition position. With the increase of filling ratio, the maximum explosion pressure rise rate will also increase.