Ultraviolet－visible detector (UV－Vis) was used to measure the solubility of RDX in supercritical carbon dioxide(SC－CO₂) at 303,308,313,323 K and a pressure range of 7-20 MPa and the relationship between concentration and absorbance of RDX/acetonitrile solution was set up at 255 nm wavelength. The results show that the solubility decreases with increasing of the temperature under low pressures 7-15 MPa. While, the solubility increases with increasing of the temperature at high pressures. The experimental results indicate that RDX′s solubility in SC－CO₂ is very low and the maximum value of solubility is only 10^－5 g RDX per gram CO₂.