Code-switching(CS)is an important field of research in sociolinguistics, drawing more and more attention from various perspectives home and abroad.Although there have been extensive researches and achievements in this area, they mainly focus on oral data analysis.Few people have ever attempted to explore CS in the field of literature.The paper thus attempts to introduce CS study into the literary critics, approaching the written CS data in Qian Zhongshu’s Besieged City from a syntactic perspective.Based on the grammatical constraints proposed by Bhatt, the paper points out the constraint-ranking configuration of Chinese/English code-switching in the selected data. Code-switching (CS) is an important field of research in sociolinguistics, drawing more and more attention from various perspectives home and abroad. Yet there have been extensive researches and achievements in this area, they mainly focus on oral data analysis. Few people have ever attempted to explore CS in the field of literature. The paper thus attempts to introduce CS study into the literary critics, approaching the written CS data in Qian Zhongshu’s Besieged City from a syntactic perspective. Based on the grammatical constraints proposed by Bhatt, the paper points out the constraint-ranking configuration of Chinese / English code-switching in the selected data.