Swell is an important part in near shore wave systems and it can cause fishing shipwreck accidents due to its long duration and huge energy. Synthetic aperture radar (SAR) can image ocean waves and provide 2-dimentional wave spectra, making it an important remote tool for observing waves. In this study, swell information from orbital wave mode data of European Space Agency (ESA) ENVISAT-ASAR was used to quantify the effect of swells in wave-caused shipwreck accidents in China coastal seas. First, temporal and spatial match-up data among the wave-caused shipwreck accidents, ASAR wave mode data and model data were generated; and then the swell factors of match-up data were compared and analyzed. Conclusions are:when the shipwreck accidents happened, (1) weather systems were mostly cold air, extratropical cyclone or typhoon; (2) most mixed significant wave heights of wind waves and swells were larger than 2.0 m with swell portion greater than 50%; (3) the intersection angles between propagate directions of wind waves and swells were greater than 45°, and the shipwreck accidents happened more likely when conditions (2) and (3) were both satisfied.