Abstract: Illumination system of solid-state volumetric true 3D display requires high brightness and high stability. In order to improve the intensity of solid-state volumetric true 3D display, a kind of double-lamp illumination system based on direct current( DC) driving, parallel rays and features of light-rod illumination system was proposed. Based on the principle of etendue conservation, the converge distance was extended to realize double-lamp illumination. The doublelamp illumination system was optimized by optical simulation analysis to improve the efficiency and uniformity of the illumination system. Furthermore,the practical test system was built and measured. The result shows that the brightness on the 2-layer liquid crystal shutters in the scattering state is 41 711 cd/m2, which is 1.4 times of the brightness of the single lamp. The imaging luminance of solid-state volumetric true 3D display is efficiently improved.