The purpose of this article is to examine the relative influence of the legislative branch and executive branch in the process of lawmaking, under different periods of time of the unified and divided government. This research focuses on the fourth term of the Legislative Yuan. The research period of time ranges from 1999 February to 2002 January, divided into two periods: the first begins from February 1999 to May 2000, in which the KMT dominates the executive and the legislative branches. The second period of time begins from May 2000 to January 2002, in which the DPP dominates the executive branch and the KMT dominates the legislative branch. The research focuses on all initiations in the fourth term of the Legislative Yuan. The research findings show: First, the executive branch plays an important role in the process of lawmaking. However, the influence of the executive branch is quite different in the unified and divided governments. The initiation of the executive branch can be passed much easier and faster in the unified government than in the divided government. This finding shows that if the party of the executive branch cannot get a majority of seats in the legislative branch, it is more difficult for it to lead in the policy-making process. Secondly, The KMT and DPP legislators play quite different roles in the legislative process. In the unified government, the DPP legislators are much more aggressive in the legislative process. However, the DPP legislators are much more inactive in the legislative process since the DPP gets the executive power. On the contrary, the KMT legislators are much more aggressive in the legislative process in the divided government since the KMT loses the executive power.