Since there exists a multi-level policy making system in the market economies, choices of decision makers at different levels should be considered explicitly in the formulation of sectoral plans and policies. To support the hypothesis, a theoretical energy planning approach is developed within the framework of the theory of economic policy planning, policy systems analysis and multi-level programming. The Parametric Programming Search Algorithm has been developed. On the basis of this theoretical model, an Australian Energy Policy System Optimisation Model (AEPSOM) has been devloped and is used to formulate an Australian multi-level energy plan. The results of this study suggest that a reformulation of existing Australian energy policies is needed. This study overcomes the limitations of existing single level optimisation models, and therefore makes a significant contribution to the principles and methods for economic modelling in a market economy.