Referring to the natures of nonlinear dynamics and coupled energy domains presented by Micro-Opto-Electro-Mechanical Systems (MOEMS), a multi energy domain unified simulation language (modelica) based coupled modeling, simulation and optimization methodology is put forward. Then by choosing a micro mirror as the example, corresponding multi energy domain unified modeling and simulation processes of such a coupled micro device show the efficiency and convenience of this advanced modeling method. The dynamic input/output curves comparison also shows that the simulation result is accurate enough for system level design. At last, by using genetic optimization algorithm, the characteristics input/output curves of the micro mirror are converged to meet the ideal design requirement curves after 700 generations evolution. It proves the accuracy and efficiency of this system level simulation and optimization method.