The Cross-Strait’s ECFA is a economic excellent achievement based on Taiwanese democratic foundation. Thus, to assess Taiwanese democratic performance should be to the approach from political democracy to economic democracy. This article will explore the signing of Cross-Strait’s ECFA by way of political economics. For the Mainland China, the ECFA may promote economic development domestically; moreover, the political effects of ECFA both fastening the political power internally and strengthening peace-unification or peace-developing toward Taiwan externally. Relatively, in the stance of Taiwan, the ECFA can prevent Taiwan from the marginalization of regional integration and promoting economic development and upgrading its industries. In addition, it helps Taiwan could join the international organizations and would be conducive to the political participation within international affairs. Due to the signing of ECFA, the results are no more disputes and constraints from the disagreement both national identity and political culture. Therefore, it is worth researching further when Taiwan sign the ECFA with Mainland China and some useful suggestions are provided for the relative authorities.