Abstract: The chapter entitled with “The 24th Year of Duke Xi” in Zuo zhuan recorded a historical incident that Prince Zang,the son of the Duke Wen of the Zheng State,was killed by his father for his “Hao Ju Yu Guan” (indulgence in collecting high-rank hats).LIU Xiang,ZHENG Xuan and other scholars advocating the traditional ritual considered “Yu Guan” to be an inappropriate costume,and Prince Zang was killed by violating the ritual.But YAN Shigu of the Tang Dynasty offered a different viewpoint by interpreting “Hao Ju Yu Guan” as “getting people who know astronomy together and trying to conspire something”,the real reason for the incident.The different understandings of “Hao Ju Yu Guan” cause the different historical interpretations.However,they all accepted the rationality of Tso Chuan's historical narrative,which is the combination of narration and analysis with the distinctive feature of taking rituals as priority.Prince Zang's death for violating ritual should be viewed as the historical research of Zuo zhuan's author,but not as the objective record of history.Regarding the historical background of Duke Wen of the Zheng State's killing and exiling his sons,the real cause should be the political conflict between father and sons,and “Hao Ju Yu Guan” is an excuse only.

Key words: “Hao Ju Yu Guan”, Zuo zhuan, historical narrative, taking rituals as priority