Among the 8,700 in-service bridges in national highway, the steel bridges cover the 1600 sites and make up approximately the 20 percentage of the total amounts. Due to recent rapid increase both in traffic volume and in frequency of overloaded vehicles, the need for re-evaluating the fatigue life of the steel bridges is increasing. However, the existing fatigue life assessment method are too complicate and difficult to apply to field directly. To improve such deficiency of the existing fatigue life assessment procedures, this study reviews the fatigue life assessment methods in Eurocode and then proposes an easier and simpler fatigue life assessment procedure that could evaluate the remaining fatigue life of the steel bridges using traffic data collected from a high-speed weigh-in-motion system installed in the national highway network. The Proposed fatigue life evaluation method is as follows; 1. Calculation of fatigue resistance 𝛾𝑀f and fatigue strength Δ𝜎𝑐 used in design, 2. Calculation of partial safety factor 𝛾𝐹f for equivalent stress range, 3. Calculation of stress range Δ𝜎𝐸2 using influence line, 4. Calculation of damage equivalent factor λ, 5. Review of Fatigue state and evaluation of fatigue life. The Proposed method can omit the existing complicated and repetitive calculation. Therefore, proposed method can estimate the fatigue damage and the theoretical fatigue life simply by comparing with the existing method.