In order to meet the transfer requirement from the High-speed Railway and the Taipei Metropolitan Area, Taipei County Government plans to develop and construct a circle rapid transit line to connect with the other 11 rapid transit lines and the High-speed Railway Banchiau Station. The circle line starts from Wunshan District, extents through Shindan, Sanchong and Lujhou, then entering Shihlin and ends at Neihu District. Twenty-nine stations are proposed for the line. (Total length 33.1 km-Elevated 17.7 km and Ground section 15.4km). Detailed environmental investigations are conducted and relative plans are analyzed to predict any environment impact during the pre-construction, construction and the operation stages. The mitigation measures to avoid or lessen the adverse impacts and the environmental protection plans are also proposed.