We have investigated the electronic structure of Ru1-xCrxCaO3 using the full potential linearized augmented plane wave method within the local spin density approximation. We have obtained the spin magnetic moment centered at Ru sites from LSDA calculation. The Ru magnetic moment is consistent with the experimental estimates and is lower than the t32g↑t12g↓ electronic configuration. Cr decreases the extension of the 4d orbitals and increases the exchange coupling between electrons which may increase the magnetic moment further. Parameters of the electron-electron interaction for the RuMO3 and CrMO3 with M=Ca have been estimated by the standard LSDA-constraint technique. These calculations show that both the DOS and effective Coulomb interaction increase with the increase of Cr content.