Research conclusions：Through the long—-unit prestressed concrete continuous beam and multi—-span simply supposed steel truss girder bridge type comparison，concluded that：(1)Steel truss girder meet a simple shape，force clear，light weight，stiffness and mass symmetry，the center of gravity low seismic design principles；(2)Steel truss girder to facilitate repairs，across major rivers，have a more important military significance；(3)Steel truss girder has a smaller temperature span，do not set the track temperature regulator，to avoid the adverse effects of passenger ride comfort； (4)This article can be a highly seismic region large span bridges bridge type choose to provide a theoretical basis，for other railway bridges style selection has a certain reference significance．