The flame radiation characteristics of the single-base propellant and double-base propellant during combustion were explored for the guidance in the design of detectors for explosion suppression systems， by which the propellant flame spectroscopy experimental system was designed and constructed. The flame radiation spectra of typical single-base propellant and double-base propellant burning in air under different pressure conditions （-0.05， 0.00， 0.20 MPa） were collected and analyzed. Under atmospheric air， single-base propellant displays a weak continuous radiation only in the range of 550-650 nm. Due to the less interference of the continuous spectrum， the emission peaks of OH*， C₂*， CHO* and other emitting species can be identified in the combustion flame spectrum for the single-base propellant， and these active intermediates may be present in the flame zone during combustion. In contrast， the combustion flame radiation spectrum of double-base propellant shows the strong continuous radiation in the range of 200-1700 nm， which is attributed to that there are a large number of solid particles in its flame zone， that masks part of the emission peak information in the 200-1700 nm band. In the 1000-1700 nm band， the emission peaks of CN*， OH* and other groups were collected during the combustion of the double-base propellant. In addition， there are strong Na， K and Ca emission peaks in the flame spectra of the double-base propellant and single-base propellant， and Na， K and Ca species may come from the residual lignin in nitrocellulose. As the ambient pressure in the combustion chamber increases， the intensity of combustion radiation of both propellants is enhanced. The continuous radiation of double-base propellant in the initial stage of combustion is weak under low pressure conditions， and the characteristic peaks are similar to that of single-base propellant are collected. According to the test results， the detector for the single-base propellant should be designed based on the emission peaks of Na and K， while the detector for the double-base propellant should be designed in accordance to the peak wavelength of the continuous spectrum. The higher the ambient pressure， the lower the detector trigger threshold.