Based on literary review on authoritative comments on Lucky Jim, this paper summarizes the forms of Jim’s character flaws and then analyses their social causes: postwar era transformation during which British society transformed from postwar declining empire to a nation of benefit with superficial prosperity; reform in culture and education, especially Butler education act, which offered unprecedented chance for the younger generation from the middle and lower classes to receive education; co-existence of class barrier and division of social classes. The above analysis displays Kingsley Amis’ deep concern on British society after World War II.