Abstract: For the behavior of structure fracture, the dissipation of energy and the damage of passive encourage should be taken into consideration in the course of dynamic damage. This paper presents a comprehensive assessment method which combines the theory of energy transmission and losing (TETL) and the mechanism. The comprehensive assessment standard has been applied to the case of steel bridge, which defines the relation between the mechanism of the damage of passive encourage and welded structure parameters. These tremendously improve the combination of TETL and MDPE. The results are compared with the method of CD and target reliability, numerical simulation about steel bridge demonstrates that the method this paper presented is reasonable and effective. There are certain application prospects in the security design of the steel bridge.