A novel application architecture of smart gird dispatching and control systems is proposed based on decomposecoordinate strategy and multi-index optimization approaching control.By decompose-coordinate strategy,the higher level control center can carry out system level calculation such as load flow,short circuit current analysis,small-signal disturbance analysis,electromechanical transient simulation,electromechanical and electromagnetic hybrid simulation etc,even if the higher level control center does not collect real-time data and model data of lower level control centers.Therefore,decomposecoordinate strategy can reduce performance requirements for hardware and calculation software,and improve the convergence of system level calculation and fineness of power system models.By multi-objective optimization,smart grid dispatching and control systems can be more intelligent and have better balanced security,efficiency and environment protection.Also,in order to provide on-line power systems model for on-line applications,a state estimating method with load flow equation constraints is proposed.To provide stability margin index for on-line applications,a dynamic security analyzing method capable of giving minimal/maximal stability margins is proposed.