Invisible Man is Ralph Ellison's most important work,the hero of which is confused by the problem of his identity.This thesis will discuss the transformation of Mary Rambo in the novel.At the beginning,Mary Rambo was a symbol of hope and encouragement for the hero and a kind of salvation and redemption to him both materially and spiritually.But later,she changed from a savior to a restrictive mother.The hero became restive and guilty under her watchful and anxious care.Thus,the hero must escape her in order to continue his search for identity.