This paper reports a theoretical study on the structures and electronic and optical properties of M₂B₂₄^0/− (M = Li, Na, and K) clusters using the particle swarm optimization (CALYPSO) searching method and density functional theory (DFT) calculations. The lowest energy structures of M₂B₂₄ (M = Li, Na, and K) clusters with high symmetry are composed of three stacked ring forms, and two M atoms are located on the axis of the tubular structures. The lowest energy structure of the Li₂B₂₄⁻ cluster exhibits an open bowl-shaped structure, while the lowest energy structures of Na₂B₂₄⁻ and K₂B₂₄⁻ clusters have a double-ring tubular shape. Based on these structures, some electronic properties including charge transfer, bonding character, dipole moment, polarizability, and thermodynamic properties were investigated systematically. In addition, to provide a theoretical basis for the identification and confirmation of studied clusters, the PES, IR, Raman, and UV-visible spectra with different and meaningful characteristic peaks were simulated, which can be considered as the reference for future experimental studies.