In this research we described the effective Hamiltonian theory and applied this theory to the calculation of current-current (Q1,2) and QCD penguin (Q3,…,6) c quark decay rates. We calculated the decay rates of semileptonic and hadronic of charm quark in the effective Hamiltonian theory. We investigated the decay rates of D meson decays according to Spectator Quark Model (SQM) for the calculation of D meson decays. We obtained the total decay rates of semileptonic and hadronic of charm quark in the effective Hamiltonian according to colour Favoured (C-F) and colour Suppressed (C-S). We combined them and to added amplitude of processes colour Favoured and colour Suppressed (F+S) and obtained the decay rates of them.