This thesis consists of two parts. The first part is the commentary of my translation of Eugene O’Neill’s Long Day’s Journey into Night. The second part is the translation of the four-act play. The commentary consists of five chapters. The first chapter provides the motives, goals, and structure of the thesis. The second chapter introduces the author and the story of the play. The third chapter discusses the common problems encountered when translating a play for performance, and proposes two perspectives on “differences of historical and cultural backgrounds” and “quality of translated text”, with the discussion on translation strategies usually employed. The fourth chapter discusses the translation strategies of the play, and proposes perspectives on “maintaining the original cultural elements in original text” and “adjusting the translation in accordance with colloquial customs. The fifth chapter, for future references, comes up with conclusions and sums up my notions in translating the play.