Aluminum Powder and RDX are important metal fuels and energetic oxidants in the field of solid propellants. The ignition test of nano-aluminum/RDX mixture samples at different pressures(0.1, 0.4, 0.7, 1.0 MPa and 1.3 MPa)was carried out using a medium-pressure condenser heating experimental bench. The high speed photographer, two-color infrared thermometer and fiber optic spectrometer were used to study the combustion process.Results show that there is a significant heat evaporation stage before ignition. The duration of the flame development stage is less than that of the recession stage. Increasing pressure can effectively increase the combustion strength, but too high pressure will inhibit the flame development. As the pressure increases, evaporation stage and ignition overlap and ignition delay time is shortened. Based on the experimental conditions, the ignition delay time was 1004 ms at 0.1 MPa, and the maximum temperature was 1239 ℃. At 1.3 MPa, the ignition delay time was reduced to 319.2 ms, and the maximum temperature increased to 1441℃. At 0.1 MPa, samples burn incomplete and the self-sustaining burning time is the shortest. When the pressure is higher than 0.1 MPa, the self-sustaining burning time decreases with increasing pressure.