In order to obtain a narrow distribution, spherical, smaller size, sub-micron particles RDX, a nozzle for solution enhanced dispersion by supercritical fluids(SEDS) technology has been designed. Based on the principle of gas atomization, the ring slit structure and the microporous turbulent zone were used, so that CO₂ fluid flowed in the nozzle in high speed, the problems of block, too large size particles issues have been solved. Research shows that under the same experimental conditions, temperature is 35 ℃, pressure is 10 MPa, CO₂ flow rate is 15 kg·h^-1, RDX solution flow rate is 2 mL·min^-1, when the original internal mixing nozzle of SFP2 instrument is used, RDX particles of the distribution range from 3 μm to 15 μm are collected, the process of preparation is easy to jam. However, when the novel structure nozzle is used, sub-micron RDX particles are collected, which has a distribution range from 0.1 μm to 2 μm, and the average particle diameter is 660 nm. Both the inner diameter and the wall thickness of center hole are 0.1 mm, ring slit width is 0.1 mm, turbulent zone length to diameter ratio is 10:1, pressure difference is 1 MPa. The problem of jam in the preparation process is resolved perfectly by the novel nozzle.