Fortress Besieged was a classic of modern Chinese literature. With a typical Chinese city as the background, the novel described the life experience of an intellectual and explored the theme of human nature, human feelings, morality, marriage, education and so on. The title of the novel,"Besieged City", implied that life was as difficult as a besieged city. People were faced with all kinds of limitations and contradictions, unable to get rid of the shackles and fall into it, unable to extricate themselves. In the novel, Fang Hongjian was a typical Chinese-style intellectual. After experiencing setbacks and tribulations in marriage, education, and social interaction, he deeply realized the hypocrisy and limitations of society and life, and at the same time, he realized the true meaning of marriage and family. The novel explored the complexity and variety of human nature, showing the personalities, psychology, and values of different characters. In the novel, Zhao Hsin-mei, Sun Rou-jia, Yang Jiang, and others all had distinct personalities. Their fates and emotional entanglements constituted the main plot of the novel. At the same time, the novel also shows the complexity and variety of human nature through the communication and dialogue between the characters, so that people can deeply understand the variety and conflict of human nature. The novel also discussed the theme of marriage, education, morality and so on. The marriage plot in the novel shows the drawbacks and limitations of the traditional Chinese concept of marriage, but also shows the selfishness and hypocrisy of human nature. The educational plot in the novel showed the drawbacks and limitations of traditional Chinese education, but also showed the greed and vanity of human nature. The novel provided people with profound enlightenment and thinking through in-depth discussion of these topics.