春秋時代政治混亂，弒君弒父案件頻傳，孔子最重倫理綱常，為使亂臣賊子有所畏懼，遂直書其事於《春秋經》中。《春秋經》之書弒，有其特定的成規與義例，皆為：先記時間，其次國名，再次為弒君者，而後為被弒之君；且被弒之君必書出其名，弒君的兇手則有書出其名與未書出其名之差別，以此作為判別此弒君事件孰是孰非暨人臣弒君有罪或無罪的根據。 《春秋經．宣公二年》載云：「秋九月之丑，晉趙盾弒其君夷皋。」此條記錄明白書出弒君者「趙盾」之名，依孔子弒君書法成例，可推知弒殺晉靈公夷皋的兇手為趙盾，並且孔子判定趙盾弒君有罪。唯據《左傳》述此事件之始末謂云「乙丑，趙穿弒靈公於桃園」等等，明白指出晉靈公實為趙盾族人趙穿所殺，手刃靈公者為趙穿，而《春秋經》書云「晉趙盾弒其君夷皋」，兩者記載明顯不符合。 為釐清此歷史事件之真相，本文先從弒君者「趙盾與趙穿」之角度陳述此案之始末過程，再以被弒者「晉靈公不君」之角度探討其孰是孰非；其後再析論「經書趙盾弒其君」之撰寫書法，以探索孔子所以作此記錄之內蘊意義與筆削用心。經探究後發現趙盾之弒君實非只是《左傳》「晉靈公不君」等所載那般的單純，趙盾與靈公間有一長達十三年之久的複雜歷史，其過程糾纏著錯綜的恩怨情仇與君臣心結，晉靈公被弒如《左傳》所記兇手為趙穿，但主謀者卻如《春秋經》所載之趙盾，孔子不書趙穿而書趙盾之名有其用心與大義。

Politics were disorderly in Chun Qiu times. It was usually happened that monarchs or fathers were murdered. Confucius paid much attention to morality. In order to let courtiers be afraid of what they did, Confucius recorded every event in Chun Qiu History Book. In the book the murdered events were recorded by rule. The recording rules in paragraph were time, country's name, murderer and monarch. Monarch who was killed, name had to be written, but whether murderer's name was written or not that depended on murderer's guilty. “Zhao Dun murdered monarch Yi Goa” was found in Chun Qiu. The murderer's name, Zhao Dun, was clearly recordered. If we infer the events by Confucius's recording rules, we shall think that Zhao Dun murdered his monarch Yi Goa, Zhao Dun had guilty. But when we studied Zuo Biography about this matter, the description is “Zhao Chuan murdered his monarch Yi Goa in Toa Yuan”. Zhao Chuan was Zhao Dun's clan. The murderer's names were different in two books. This paper presents the true history and process about this event. To explore the reason why Confucius wrote with “Zhao Dun murdered monarch Yi Goa”, the recording rules are also discussed in detail.