Abstract: According to the welded girders with trapezoidal corrugated webs, FEA models was established based on several characterization stress methods(nominal stress method, hot-spot stress method, equivalent structural stress method), which was used to study characterization stress distribution, analyze crack initiation location, evaluate fatigue life and compare the effect of different characterization stress by different methods. Results show that the nominal stress curve and hot-spot stress curve show the similar distribution with a certain corrugated characteristic, but crack initiation location and fatigue life cannot be determined and predicted exactly. However, equivalent structural stress curve has severe corrugated characteristics which can predict crack initiation location accurately and evaluate the fatigue life reliably. Consequently, equivalent structural stress method was recommended as the control variable to evaluate fatigue life of welded girders with trapezoidal corrugated webs.