The band structure and the density of states of CoSi2 were calculated by means of the self-consistent LMTO method. The peak positions of the calculated DOS were in reasonable agreement with the corresponding peak positions of the synchrotron radiation photoemission studies. Our calculated results showed that the main characteristic of the electronic structure of the silicides CoSi2 and NiSi2 were dominated by the hybridization between the transition metal-3d orbitals and the silieon-3p orbitals. The bonding in CoSi2 and NiSi2 was different from that of bulk Si, where the bonding was due to the sp3 hybridization of Si atom orbitals.