洪峰流量及暴雨強度之頻率分析常作為水工結構物防洪與排水的設計標準，但受到降雨範圍及地文因子等因素的影響，同一場颱風或暴雨之河川尖峰流量及降雨量通常不會有相同的迴歸期，亦即二者之關聯具有若干的不確定性，因此以聯合機率分布的形式來研究應是較適宜的方法，此為本文的主要研究目的。由於颱風或暴雨期間之洪峰流量及短延時降雨均為極端事件，因此本文以雙極端值分布來建立洪峰與暴雨之關聯，並由此聯合機率分布推導出洪峰與暴雨的聯合迴歸期及條件式迴歸期公式。文末則將此方法應用於八掌溪流域以建立該流域颱風或暴雨期間洪峰流量與暴雨之關係並推估不同迴歸期之洪峰量及暴雨量。 Frequency analysis of flood peak and storm rainfall is often used as design criteria of hydraulic structures. However, several factors cause the return period of respective flood peak and storm rainfall for a same event different. Namely, the relationship between flood and storm is not deterministic. Therefore, a better approach is to study the dependence structure between the flood peak and storm rainfall is using joint distribution. In this study, a bivariate distribution is used to model the phenomena of flood peak and storm rainfall. Both the flood and storm are extreme hydrologic events, hence, a bivariate extreme value distribution is used in this study. The joint and conditional return period are also derived based on the bivariate distribution. Pachang river is used as a case study to illustrate to the proposed models.