The electronic band structure of  has been calculated using the self-consistent full potential non-orthogonal local orbital minimum basis scheme based on the density functional theory within the local density approximation. The Ru 4d and O 2s, 2p states play important roles near the Fermi level. Our study shows that there is a small gap near the Fermi level. This small direct gap has a magnitude of about 0.3eV along  line. The calculated magnetic moment of  within LDA scheme is  close to the experimental value of

 electronic structure.