The weakly charged colloidal system consisting of one or two charged large-spheres immersed in charged small-spheres confined between two charged plates are studied through Monte Carlo simulation. The electrostatic energy of the system is analytically calculated using the hyper-sphere method, and the depletion interactions between the charged large-sphere and the charged plate, and that between two charged large-spheres, are obtained using the acceptance ratio method. Compared with the corresponding uncharged hard sphere systems, it is found that, in the charged systems, the depletion forces between the charged spheres and the two charged plates are strengthened by the electrostatic interactions.