<p>Storm surge events (SSEs) involve multiple hazard-causing factors, such as surges, extreme rainfall, strong winds, waves, and ocean currents, which have destructive impacts on coastal regions. For a quantitative multi-hazard assessment of SSEs, this study introduced the concept of the storm surge event seawater-atmosphere system (SSE-SAS) and proposed the system energy equivalence (SEE) model from a systemic energy perspective. SEE was obtained by employing a parameterization approach, and the hazard index (HI) and the concept of most significant hazard (MSH) were adopted to evaluate the severity of SSE-SAS. SEE at five stations in the Shandong Peninsula was calculated from 2005 to 2019, and probability analysis and hazard assessment were further conducted. Results show that the SEE of SSE-SAS ranges from 0.029×10³ to 30.418×10³ J/m², and it exhibits an insignificant decreasing trend from 2005 to 2019. The SEE of SSE-SAS in the west of the Shandong Peninsula is greater than that in the east. Moreover, storm waves, storm surges, and storm rainfall are the major contributors to SEE, which exhibit different spatial patterns and characters in different SSE-SAS types. The HI of SSE-SAS at five stations is no more than medium hazard level, with MSH at return periods of 2-to 4-year level. This study provides a new approach for quantifying multi-hazard SSEs, which offers scientific insights for regional multi-hazard risk reduction and mitigation efforts.</p>