The invention relates to a test device, in particular to a device for installing a blasting pressure reducing diaphragm. The device for installing the blasting pressure reducing diaphragm comprises an inner throat bushing, a seal strip, a compression device, a channel, a channel inlet, a compression device, an upper guide rail and a lower guide rail device. The channel inlet is located at the position adjacent to a cabin body, and a seal door is further designed at the position of the channel inlet. The upper guide rail is arranged at the top of the channel, a lower guide rail device is designed at the bottom of the channel, and the compression device exerts force on the blasting pressure reducing diaphragm. According to the device for installing the blasting pressure reducing diaphragm, the channel inlet is processed in the outer side face at the position adjacent to the cabin body, the blasting pressure reducing diaphragm is pushed into the preserved installation position through the upper guide rail and the lower guide rail, and then installation of the blasting pressure reducing diaphragm can be completed by compressing the compression device. The whole installation process only requires a few minutes, working efficiency can be greatly improved, and installation can be completed by one person in the installation process, so that the device for installing the blasting pressure reducing diaphragm is convenient and safe to operate and free of potential safety hazards caused by accidents.