成本效益分析常被用來評估一項計畫或方案的經濟可欲性（economic desirability）。以美國政府為例，成本效益分析最早應用在新政（New Deal）時期的洪水控制計畫上，稍後並擴大適用於其他公共事業的經營分析，直到1960年代才進一步應用到聯邦政府的預算過程，成為擬編設計計畫預算（PPBS）的分析工具。我國在民國八十七年修正的預算法第三十四條中也規定，重要公共工程及重大施政計畫，應先行製作選擇方案及替代方案之成本效益分析報告，並提供財源籌措及資金運用之說明，始得編列概算及預算案，並送立法院備查。從國內外的發展趨勢來看，成本效益分析在政府決策上鑿斧的痕跡將會越來越普遍。 　　本文以剖析戚本效益分析在政府決策應用上的基本議題為軸心。首先，概略介紹成本效益分析在中外公共部門的實施情形。其次，逐一討論實施這項分析工具經常涉及的一些基本議題，包括從誰的立場來考量一項政策所有相關的影響?各項成本和效益的估價問題？如何處理時間、風險和不確定的因素？又如何將預算限制和分配效果納入政府決策上的考慮？以及為何只能追求潛在的薄瑞多效率（potential Pareto efficiency）？再次，說明成本效益分析在實務應用上經常遭遇的限制因素。又次，綜合討論各界對於成本效益分析的批判與質疑，提出經濟分析的邏輯是否會減損民主價值等反思的觀點。最後，以成本效益分析來促進理性決策和理性預算的主張，來作為本文的結語。

　　Cost-Benefit Analysis(CBA) is normally used to evaluate the economic desirability of public programs. Given its increasing importance in the governmental decision-making, this paper is first to explore several critical issues concerning the utilization of CBA in the public sector, such as identifying relevant impacts, monetizing impacts, discounting for time and risk, and choosing among policy alternatives under consideration. This paper is further to describe the three major weaknesses of CBA in the governmental decision-making process. As a decision -supporting technique, the implementation of CBA is very expensive and time-consuming. In addition, many decisions involving in the CBA are still controversial since they are not only technical issues but also pertinent to the value judgement of policy analysts. The utilization of CBA is also intruded by the political process which often flocks with many conflict interests and preferences. From the standpoint of ethic and philosophical critiques, the paper finally discusses the adequacy of utilizing CBA in the representative government.