Lu Xun's A Trivial Matter was a short story that revealed the complexity of social class and human nature by describing the encounter, communication and misunderstanding between the protagonist and a woman. The clue of the novel is the emotional entanglement between the protagonist and the lady. Through the detailed description and dialogue, it shows the inner contradictions and psychological changes of the protagonist. At the same time, the novel also hinted at the social class and interpersonal relationships of the protagonist through the woman's words, deeds and attitudes. In terms of writing techniques, Lu Xun used contrast and irony. He contrasted the protagonist with the lady, emphasizing the protagonist's kindness and integrity while satirizing the hypocrisy, selfishness and bureaucrats in society. In addition, the novel also used detailed descriptions and metaphor techniques to enhance the novel's expressiveness and artistic appeal. A Trivial Matter is an excellent novel that presents the good and evil and complexity of human nature in a concise and profound way through emotional clues and social reality clues.