Gold nanoparticles have great application potential in laser ignition due to their large light absorption cross section and spectral selectivity. Based on the structure and size of nanometallic composite explosives prepared in the present experiment, three types of the optical absorption models for composite explosives are constructed. They are respectively Au-core RDX-shell spherical nanoparticles, Au-RDX-Au-RDX uniform alternate core-shell spherical nanoparticles, and the RDX-core Au-shell nanoparticles. The near-infrared light absorption spectra of nanogold composite explosives are analyzed using the discrete dipole approximation method (DDA), and the effects of core shell sizes and surrounding ambient media on near-infrared laser absorption properties are considered for various models. The optimal structure parameters of the nanocomposite structure under near-infrared laser irradiation are obtained. The results show that when being prepared into a nano-scale Au core RDX shell spherical particle, it has a high light absorption for the near-infrared laser (800 nm) wavelength, the corresponding core shell size is about respectively 60 nm and 20 nm, and the absorption intensity in water is stronger than that in the air.