Type ZJ200 Portable Steel Bridge (also called Prefabricated Highway Steel Bridge) is a through-type bridge with the roadway being carried between two main girders. The trusses in each girder are formed by 10-foot panels pinned end to end. The Bridge is designed to solve the problems of the insufficient bearing capacity, the narrow vehicle lane width and the low fatigue life of the existing “321” Steel Bridges. The Finite Element Analysis (FEA) and structure realibility theory being applied to optimization design of bridge, the fatigue life of ZJ200 Bridge is improved. It may play an important role in improving emergency traffic support capacity and perfecting the emergency traffic support system.