Experimental opacity data are used to evaluate the opacity models and their accuracy of the calculated results. In order to study the opacity of carbon material in the shell of the inertial confinement fusion ignition target, the experimental study of the spectrally-resolved opacity of radiatively heated carbon plasma is carried out on the Shenguang III prototype laser facility. Eight nanosecond lasers are injected into a conical-cylindrical gold hohlraum and converted into intense X-ray radiation, the high-temperature plasma is obtained by radiatively heating the CH film in the center of the hohlraum. Temporal evolutions of temperature and density of carbon plasma are simulated with the Multi-1D code. By using a spatially-resolved flat-field grating spectrometer combined with the ninth beam smoothing surface backlight technology, the absorption spectra of CH sample and the backlighter spectra are measured in one shot. Finally, the experimental transmission spectra of carbon plasma (with a temperature of 65 eV and density of 0.003 g/cm³) in a range of 300–500 eV are obtained and compared with the calculated results of a DCA/UTA opacity code. The datasets presented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00213.00153.