Based on the engineering projects of the east and west extended sections of Shanghai No.2 metro line, the Xin-Min light-rail transport line and Xi'an metro line, etc. the main principles several aspects arid factors which should be considered on selection of the type of viaduct for urban rail transit are explored systematically in this paper. Combining with these particular engineering projects, different types of bridge structure and bridge pier for the viaducts are introduced in detail, and the proper selection schemes are recommended as reference.