本文利用追蹤資料向量自我迴歸模型，檢證2003～2012年中美外援非洲的動機與成效。結果顯示，大國外援有相同之處：兩者外援目的，都不是基於國際道義考量，但大國外援也存在差異的地方：中國外援以現實利益為主，目的為確保其企業海外投資安全。美國外援則不局限在經濟利益而已，更加側重非傳統安全領域;換言之，美援強調的是綜合利益。中美兩國外援模式差異，肇因於彼此政府對自身所處國際體系地位的認知不同。 In this paper, we used the panel data vector autoregression model (PVAR) to test motivation and effectiveness of the U.S. and China's foreign aid (FA) in Africa. Empirical results show similarities in the great power's foreign aid: the purpose of both great power's FA is not based on international moral considerations. However there are also major differences between these two great power's FA. Chinese FA is based on real interests and mainly aims to ensure safety of its outward foreign direct investment (OFDI). The U.S., on the contrary, focuses more on non-traditional security issues after the Cold War. In other words, the U.S. FA emphasizes on comprehensive interests. Differences in motivation and effectiveness between China and U.S. FA arises from the government's awareness of its own status in the international power system.