This paper is arranged in the following framework: in the first chapter, a general review is made about the research background, including the researches on William Somerset Maugham and his work The Moon and Sixpence, and the research significance as well as the structure of the paper. Chapter two is an overview of Sartre’s Existentialism. The following two chapters are the main body of the paper, including absurdity, choice and responsibility. Ridiculous human-human and human-society relationship can be seen in chapter three. And in chapter four, it explores Strickland’s escaping from comfort zone, getting rid of physical sex and ruining off painting. The fifth chapter is the concluding part that summarizes the main points of the full text, which tries to analyze the value and significance of the Existentialism in Maugham’s The Moon and Sixpence.