Abstract：The Mayor of Casterbridge claims a unique place among Thomas Hardy's series of"Wessex""Character and Environment"novels.The subtitle of the novel is A Story of a Man of Character.The hero Michael Henchard is a person of great passion and strong character.Sometimes, he is bigoted and rude, at the same time, he is upright and decent, which make up his complex and changeable character.Based on psychological theory, people's character is determined and shaped by their personality structure.This paper tries to use Sigmund Freud's theory of personality structure to analyze the complexity of Henchard's character.Freud's theory of personality structure consists of three parts: id, ego and superego.During Henchard's struggle among id, ego and superego, the three systems of the personality structure are becoming increasingly harmonious and poised, thus his character is gradually becoming more mature and perfect.

Keyword：Freud;theory of personality structure;Henchard;character;