Based on first principles, we use GGA and PAW method in the framework of density functional theory to investigate electronic structure of perovskite ruthenate CaRuO3. Additionally, we also perform GGA+U calculation to include the on site Coulomb interaction of Ru ion. The total-energy studies show that CaRuO3 stabilize in metallic conducting ground state with ferromagnetic ordering. Furthermore, the calculation show that it is necessary to carry out GGA+U scheme and structure optimization on this system.