本文針對《春秋》經傳記載對外戰爭之日期干支，以表格方式臚列排比，檢視《禮記‧曲禮上》「外事以剛日」之說是否有所依據。經本文分析得三項結論：第一、春秋時人有意識選擇「剛日」發動戰爭。第二、以姬姓為主之北方中原諸國選擇「剛日」比例高於整體平均值，以楚國為主之南方諸國則低於整體平均值。第三、隨時間遞嬗，自春秋早期至晚期，選擇「剛日」比例大致有下滑趨勢。

By listing all the dates of external wars recorded on the classic of Chunqiu and its commentaries, this article aims to observe the validity of the idea that external undertakings should be commenced on the odd days (waishi yi gangri), which occurs in the first chapter of Quli in liji, arguing that three points should be paid attention: 1. For peoples during Chunqiu period, declaring a war on the odd days is of special significance. 2. In fighting on the odd days, northern states of noble Ji are higher than average, which is contrary to the case of southern states, in which the state of Chu is the leader. 3. It can be seen that from early Chunqiu to its late stage, there had been a decrease in taking odd days as an option for declaring a war.