The Rio Declaration on Environment and Development 1992 determined the principles of public participation and precautionary principle of environmental protection. The Environmental Impact Assessment Act (EIA Act) in Taiwan entered into force on 1th January 1995, which has implemented those principles. The features of the EIA in Taiwan, compared with the law systems of the USA and Germany, are based on the two responsible administrative agencies for a whole project, two-staged procedures in the EIA, and the multi-leveled procedures for the permission of a project. In addition, the EIA represents as an independent administrative procedure, and the conclusion of the EIA has legal character and a decisive effect to the project permission. Procedurally, both the public participation and the disclosure of the information confront dilemma and weakness in law dimension. Regarding the latter, the legislation should base on the academic researches and the quality as well as the quantity need to be improved. As for the question about the credibility and acceptability of the public participation, the resolution could be the amendment of the legal framework of the EIA Act, and the legal principles of the hearing procedure in the so called planfeststellungsverfahren should be established in the EIA Act. Not only the legality, but also the legitimacy of the EIA should be emphasized within the cooperation and the dialogue between the people and the administrative agencies.