Using the density functional theory (DFT), the geometrical structures of the (Li2F)nM (M=Li, Na, K; n=1, 2) clusters were optimized at the B3LYP/6-311+G* level of theory, and all of ground-state structures were determined, while their chemical stabilities, electronic properties and infrared spectra were systematically discussed. The calculated results showed that the (Li2F)M (M=Li, Na, K) clusters had the same double-triangular geometries, whereas the structures of (Li2F)2M were distinctly different. It was also found that the (Li2F)Li and (Li2F)2Na clusters were strongly stable due to the large binding energy and HOMO-LUMO energy gap. The high chemical stability can be explained by the strong sp hybridization to form the σ bonds (e. g., HOMO, LUMO). Meanwhile, it was predicted that the (Li2F)2K cluster could be considered as novel superalkali compound because of its low ionization potential (4.23 eV). In addition, we simulated the infrared spectra of these (Li2F)nM clusters, and assigned the main vibrational peaks for further experimental references.