The thesis is based on the research of 「Anti-secession law」enacted by China. Cross-strait relation is the main scope of this research that covers the time from Nov.2002－ Hu inherited the 4th leader of China at 16th National Representatives Convention－to the present after 「Anti-Secession Law」was announced. Cross-strait relation and policy towards China are always being the most sophisticated political issues between China and Taiwan, as well as being the significant factors that determine the direction of Taiwanese future. China, in particular, thought that Taiwanese government’s altitude towards “One-China Policy” is ambiguous and avoid discussing the issue all the time; furthermore, the pursuit of independence on this island is getting rampant. As President Chen Shui-Bian proposed “One Side One Country,” “Referendum,” “Founding a new Constitution,” and “Amending the official name of Taiwan,” which make Mainland China begin to shift its policy toward Taiwan significantly. These are the reasons why China posed the 「Anti-Secession Law」. For many years, China’s description of policy towards Taiwan merely exists in the government’s statement, leader’s speeches, or in the important announcement of the Ministry of Foreign Affairs in China. The Anti-Secession Law sheds a new light on the cross-strait relation. It not only is a legislated One-China Policy insisted by China in policy towards Taiwan, but also effectively restrains the legal independence in Taiwan, firmly upgrading the consciousness of anti-secession onto national-level consciousness; moreover, it offers China a law-based support on policy towards Taiwan. Therefore,「Anti-Secession Law」as well as Four Opinions, posed by chairman Hu in order to develop cross-strait relation, embodies a new policy and a new thinking of the Chinese new generation leadership, and is the keynote of policy towards Taiwan in the future, acting as a powerful and legal weapon to maintain the peace between China and Taiwan. It is obvious that Anti-Secession Law is enacted against Taiwan, so how we treat the difference of Mainland China’s policy towards Taiwan before and after instituting this law, how we face the challenge caused by it in our society, how to manage the constructive change resulted form cross-strait relation and the peace across the strait, and which policy should Taiwanese adopt as a response. All of the above are the chief motives and purposes of this research paper. At last, the paper will propose some feasible directions in connection with the trend of cross-strait relation, the possibility of re-initiating cross-strait communication, and the development of cross-strait relation in the future.