In Qian Zhongshu's Fortress Besieged, the term "besieged city" referred to the social environment and interpersonal relationships that people lived in. It was like a besieged city. It seemed that the walls were high, making it impossible for people to escape, but in fact, it was difficult to find a way out, making people feel trapped and unable to extricate themselves. This besieged city was described by Fang Hongjian. After entering the besieged city, he found that the various problems and difficulties he faced, including marriage, career, friendship, and so on, were like a besieged city that made people feel confused and lost. At the same time, the outside world was filled with all kinds of temptations and challenges that were hard to resist. Through Fang Hongjian's perspective, Qian Zhongshu used this besieged city to describe the various ills of Chinese society and the complexity of human nature, profoundly revealing the weaknesses and contradictions of human nature, and also showing the author's insight and thinking about human nature. Therefore, Fortress Besieged was regarded as a classic of modern Chinese literature and had a profound impact on Chinese literature and the world of thought.