Beloved is a novel that was published in 1987 by the celebrated American author, Toni Morrison, the first black woman to win the Nobel Prize in Literature, while this book had been a Bestseller for 25 weeks and won countless awards including the Pulitzer Prize for Fiction. Morrison used a lot of postmodern writing techniques in Beloved. As postmodernists usually do, she showed a highly free spirit in her creation and criticism, which includes high degree of indeterminacy and ambiguity. Toni Morrison's Beloved reflects the characteristics of postmodern literature and in particular, shows ambiguity in the narrative way, character identity, the theme and so on. All of these characteristics make it difficult for us to understand Beloved thoroughly. However, it is the ambiguity and indeterminacy in Beloved that makes it more artistic and creative, while reflects Morrison's excellent writing skills and deep thought as well. In this way, she leaves large imagination space for the reader, and thus leads the reader keep constructing actively while reading. In this paper, the ambiguity and indeterminacies in Beloved are mainly analyzed in order to understand the novel better.