The effects of copper micro-particles on the detonation characteristics of RDX powder were investigated in a horizontal shock tube with internal dimensions of 100 mm diameter and 4 m length using an instantaneous spectrum detection apparatus. The emergence time and emission spectral intensity of the main products such as NO2, H, C2, O, CO, CH2O, CO2 and H2O were observed by a TDS5054 oscilloscope. With or without the addition of copper micro-particles into RDX, NO2 appears first in every experiment, which is in agreement with theoretical results. However, the addition of copper micro-particles to RDX can shorten the emergence time by 7–18%; it can also increase the peak blast pressure by about 133%. In addition, O2, H2O and CH2O in various quantities were introduced into this experiment, respectively, which indicate that O2 can obviously affect the results that may shorten the emergence time of NO2 by 31% and increase the peak blast pressure by 167%.