近年來，全球氣候變遷問題已嚴重影響人類生活，而世界各國也逐漸意識到已開發國家和開發中國家必須共同合作以解決此問題。京都議定書中的清潔發展機制 (CDM) 即是讓已開發國家與開發中國家共同實踐減量目標的一種彈性減量機制，然而過去文獻對於其減排成效的看法並不一致。有鑒於此，本文以參與 CDM計畫的 20個開發中國家和 16個已開發國家為研究對象，探討 CDM計畫對其2003至 2008年二氧化碳減量之影響。根據兩階段最小平方法之固定效果模型的實證結果顯示，CDM計畫能減少開發中國家的二氧化碳排放量，但經認證的排放減量額度 (CERs) 有被過量核發之現象；另一方面，CDM計畫對已開發國家的減排效果則無影響。 In recent years, global climate change problem has seriously affected humans’ life. There is a consensus that the developed and developing countries have to work together to solve the problem. Clean Development Mechanism (CDM) is one of the flexibility mechanisms defined in the Kyoto Protocol, and it allows the developed countries, in cooperation with developing countries, to fulfill the emission-reduction targets. However, the emissions abatement effects of CDM in the literatures are diverse. Accordingly, this paper uses 20 developed countries and 16 developing countries as an empirical case to examine the impact of CDM on carbon dioxide emissions abatement from 2003 to 2008. According to the fixed effects and two-stage least squares model, CDM projects did reduce the carbon dioxide emissions of developing countries, but the certified emissions reductions (CERs) were excessively issued. On the other hand, CDM projects didn’t have an impact on the home countries’ emissions of developed partners.