Skopos rule: The skopos principle holds that the primary principle that all translation activities should follow is "the principle of purpose" and the translations should be able to function in the context of translations and cultures, which depend on the recipient's expectation。 The purpose of the translation action to determine the purpose of the entire translation process, that is the results determine the methods。 But the translation activities can have lots of purposes, these objectives are further pided into three categories: (1) The basic purpose of the translator (such as making a living); (2) The purpose of communication (such as enlightening readers); (3)The purpose to be achieved by the use of a particular means of translation (such as the way in which in order to illustrate the particularity of the grammatical structure of a language in the use of literal translation)。 However, under normal circumstances, "purpose" means the purpose of communication of the translation which means that "translation in the translation of social and cultural context of the translator into the language of communication function" (Vermeer 3)。 Therefore, the translator should specify the specific purpose in the given translation context and decide which translation method she or he need to use according to this purpose - literal translation, paraphrase or between the two。

     Coherence rule: Coherence rule refers to that the translation must conform to coherent standard, which means that the translation has the readability and acceptability and makes itself meaningful so that the recipient can understand and communicate in the language translation as well as the use of translation in the context of communication。

      Fidelity rule: Fidelity rule refers to that the original text and the translation should exist the inter-lingual coherence。 This is similar to the other translation theory which is faithful to the original text, however, the original faithful degree and form depend on the purpose of the translation and the translator's understanding of the origin。文献综述

     Loyalty principle: This principle is proposed by Nord。 She found that this theory has two major shortcomings: First one is that because of the differences in cultural patterns, people in different cultural backgrounds have different views on good translations; besides, if the purpose of communication required by the purpose of the translation with the original author's intention is just the opposite, then we will abide by the principle of purpose and contrary to the principle of faithfulness (Nord 13)。 Thus, Nord brings up loyalty principles to deal with the relationship between cultural differences and translators。 Nord believes that the translator has a responsibility for the recipient of the translation and must explain to them what they are doing and why。 This is one aspect of the loyalty principle。Another aspect of the principle is to ask the translator to be faithful to the original author。 The translator should respect the original author, balance the target language with author’s intention (Nord 14)。 Therefore, the loyalty principle is mainly concerned with the relationship among the translator the original author, the client, the recipient and the participants during the translation process。 Nord proposed that the translator should follow the guiding principle of "function plus loyalty", thus perfecting the theory。

     In short, these four principles constitute the basic principles of skopos theory, but the principle of coherence, loyalty and loyalty principle must submit to the principle of purpose, which is the primary principle of skopos theory。