An idiom is a phrase which is an established and fixed part of a particular language. Idioms are the essence of language and they bear the cultural characteristics and cultural information of a nation. The culture differences reflected in idioms are mainly shown in four aspects. They are differences in context, custom, religion and history. Idioms’ characteristics have a close relationship with source. The two languages between Chinese and English have some similar cultural characteristics. These differences and similarities make translation of idioms quite difficult. Therefore, cultural translation methods are very important. In order to have a better transmit in idioms culture, we should avoid making mistakes in idiom translation. English-Chinese translation is one of the important means of learning English, especially the translation of English idioms. Translators often need careful scrutiny, should not take the words literally. Making the translation of idioms is in line with the idioms using habits, but also with their implied meaning. This paper tries to analyze some idioms from the background knowledge. Therefore, discussion on correct understanding idioms is an important prerequisite for translation.