This paper first attempts to explore the increasing descensus of national identity of Taiwanese voters based on electoral survey data. Second, factors that determine individual s orientation in diversified national identity are analyzed and the relationship between descensus of national identity and partisanship as well as partisan vote-choices are also causally modeled. As the survey data collected between 1991 and 1993 show, there was an increasing trend of the descensus of national identity. And, individual's Taiwanese-Mainlander ethnicity are the most important factors in determining individual's DPP-KMT partisanship. Finally, individual's national identity and partisanship are significant predictors for partisan vote-chices, and this causal model is held against different time as well as different elections. This paper concludes that the increasing descensus of Taiwanese national identity has been and will be closely linked to the growing of partisanship and to partisan vote-choices, that is, Taiwan's recent elections have been related structurally to nation building rather that functionally to select elective offices.