The authors present a model to describe high-T_c superconductivity in doped planar CuO₂ systems. Each doped hole on the oxygen site interacts through strong antiferromagnetic (AF) coupling with two neighbouring copper holes to form Cu-O spin singlet pairs and interacts with a Cu-RVB state to lead to the condensation of O holes in momentum space, which is responsible for the superconductivity. The ground state of this system and the spin correlation of Cu and O holes are also studied. The results are in good agreement with previous works.