Although Philip Roth’s fiction has received severe criticism from most readers and critics for its bold description of sexuality, it reveals the evolution of sex ethics in contemporary America and Roth’s own understanding of sexuality. Taking The Dying Animal as an example, this paper probes into the questions above. Philip Roth’s sexuality writing reflects the contemporary American history in the novel and influence of traditional Jewish ideas of sexes. Roth’s sexuality writing in the novel promotes the development of the story, and is mingled with Roth’s understanding of ethical ideology, and shows his concern about sense and sensibility of individuals.