Abstract: The minimum detonation length of cartridge for CO₂ fracturing device is tested, and the blasting experiment was carried out stepwise by using the control variable method, and the blasting effect is analyzed theoretically. The optimal length of the cartridge in engineering application was discussed. The method of the obtained safety detonation volume and the method of increasing the explosive power of different types of fractures have a guiding role in coal seam gas drainage and rock fracturing.