Idiom,the cream of the language,is a fixed group of words or a single word,or even a sentence with a special mean ing that cannot be guessed from the literal meaning of its components.In the long history,animals and human beings coexist on the earth,interact on each other and depend on each other.While animals are closely linked to the life of human beings in the whole history,gradually,people are inclined to associate some animals with certain qualities or characteristics with human beings also with the same features,then,a number of animal idioms get into human’s language.In this thesis,the author will accomplish the purpose by finding out the duality of human evolution,more animal idioms and analyze the reasons for the different figura tive images such as living environment,religions and customs.