Based on Miner’s rule of linear damage accumulation and S-N curves, the fatigue strength assessment of wave-piercing catamaran(WPC) is predicated by employing the spectral-based analysis. Firstly, a finite element model of the ship structure was built. Then, the principal stress transfer functions of hotspots were calculated at different wave frequencies in several wave headings. The wave scatter diagram of the North Atlantic was used as wave loading spectrum. The fatigue strength assessment of the hotspots was conducted by using two types of S-N curves (curve II and curve III) which were recommended by DNV rules.. The results show that several hotspots could not meet the service demand and must be improved. The assessment result is helpful for the structural design of the joints of similar wave-piercing catamaran(WPC) design and development