The paper explored the urgent needs of scientific development practice and economic development pattern transform. The integrated economic effectiveness of energy conservation and intensity decrease were analyzed,and the economic rationality of energy conservation priority strategy was identified. The paper assessed the integrated economic benefit of energy conservation effort during the "11th Five-Year Plan"  period. With data and facts, it was approved that the energy conservation efforts achieved great economic benefit. The paper analyzed the macro-economic effectiveness contributed by efforts of energy conservation in the "12th Five-Year Plan"  period to support the transform of economic development pattern, and to achieve long term sustainability of economic growth.