Traditionally, span analysis determines the maximum allowable free span length based on the condition that no vortex induced vibration (VIV) will happen and the assumption of strength ultimate limit state (ULS). The cost of span mitigation rises rapidly with the increase of water depth. Free span analysis based on fatigue life could remarkably increase the maximum allowable span length and cut the engineering cost. We present the free span analysis method and criteria for subsea pipeline. Based on the engineering project which is the first time to use fatigue limit for pipeline design, the free span analysis is conducted by fatigue limit state (FLS) and finite element method, and the results minimize the number of span mitigation.