The superhalogen properties of polynuclear structures without halogen ligand are theoretically explored here for several [M2(CN)5]-1(M= Ca,Be)clusters.At CCSD(T)level,these clusters have been confirmed to be superhalogens due to their high vertical electron detachment energies(VDE).The largest one is 9.70 eV for [Ca2(CN)5]-1 which is even higher than those of corresponding traditional structures based on fluorine or chlorine ligands as shown in Fig.1.