本文先建構「半總統制」的運作類型：「多數政權制」與「少數政權制」以及各次類型。再從歷史的角度比較「九七憲改」後的憲政運作，以蕭萬長、唐飛、張俊雄三位行政院長與總統、立法院、政黨之關係，分析我國憲法規範與憲政運作之問題。李登輝的蕭萬長內閣，是過去憲政運作的持續，行政院院長是總統的執行長；陳水扁的唐飛內閣，其主要的困境繫於與陳總統的關係上；張俊雄內閣的問題則在與立法院的互動上。由於陳水扁所屬政黨與立法院中的多數黨不同，因此，後兩者可以視為對「九七憲改」的嚴酷考驗。今年年底的立法院改選，代表新民意的國會政黨生態以及陳水扁的內閣選擇，是影響我國日後憲政體制走向的重要關鍵。

　　　　　This article studies operational types of the "semi-presidential system": majority regime system, minority regime system, and other sub-systems. The focus is on Taiwan's constitutional operations after the 1997 constitutional amendments. The paper analyzes the problems in Taiwan's constitutional statues and operations by comparing Premiers Vincent C. Siew, Tang Fei, and Chang Chun-hsiung and their relationships with the president, the Legislative Yuan, and the political parties. In the era of President Lee Teng-hui, constitutional operation was a continuity of past practices. Premier Siew served as the chief of staff to the president. Tang Fei's problems stemmed mainly from his awkward relations with President Chen Shuibian For Premier Chang Chun-hsiung, the main problem has been the difficult executive-legislative interactions. The cases of Premiers Tang and Chang are severe tests to the constitutional system after the 1997 amendments because President Chen's party does not enjoy a majority in the Legislative Yuan. The legislative elections in December 2001 will produce a new congress representing the newest public opinion. The new power structure in congress and President Chen's decision to reshuffle the cabinet are keys affecting Taiwan's constitutional system in the future.