Most people considered London a living symbo of rugged individualism, but in a note to Upton Sinclair, London wrote, “One of my motifs, in this book, was an attack on individualism(in the person of the hero). I must have bungled for not a single reviewer has discovered it.” The contradiction between his works and himself is worth inquiring and investigating. The story exposes the cruel fact that the amount of wealth one owns decides the social status he is in the capitalis society. And it criticizes the hypocrisy, the snobbish eye and the concept of money as the first priority of the upper class. At the same time, the author shows his sympathy with laborers who live in the bottom of the society. This essay is aimed at analyzing the methods to express author’s naturalism theory and the relevance to our life. Most people considered London a living symbo of rugged individualism, but in a note to Upton Sinclair, London wrote, "One of my motifs, in this book, was an attack on individualism (in the person of the hero). I must have the contradiction between his works and himself is worth inquiring and investigating. The story exposes the cruel fact that the amount of wealth one owns decides the wealth of one owns decides the social status he is in the capitalis society. And it criticizes the hypocrisy, the snobbish eye and the concept of money as the first priority of the upper class. At the same time, the author shows his sympathy with laborers who live in the bottom of the society. This essay is aimed at analyzing the methods to express author’s naturalism theory and the relevance to our life.