Two new quaternary chalcogenides, Na6CdSb4S10 and Na3CdSbSe4, were successfully synthesized by the high-temperature solid-state reaction in vacuum-sealed silica tubes. Note that Na6CdSb4S10 crystallizes in the C2/c space group, whereas Na3CdSbSe4 crystallizes in the P21/c space group. As seen from their structures, Na6CdSb4S10 exhibits a three-dimensional (3D) framework structure composed by the interconnection of isolated [(Cd/Sb)2Sb2S10] clusters and two different layers formed by the NaSn (n = 4, 6) units; besides, the structure of Na3CdSbSe4 is composed of isolated ∞(Cd3Sb2Se12)n chains and 2D layers formed by the NaSen (n = 5, 6) units. Their optical performances (bandgap and Raman spectra) were also investigated. Moreover, theoretical calculation was used to analyze the structure–performance relationship of Na3CdSbSe4. [ABSTRACT FROM AUTHOR]