Coherence is one of the important concepts in linguistics。 It mainly refers to internal contact or relativity in semantics or content that is each concept and relationship in the scenario described by language must be connected and associated in order to keep the whole content consistent and the coherence of semantic。 Semantic coherence includes coherence in semantics and pragmatics, also in the internal discourse, the coherence of language and the formation of logical relation among sentences。 The establishment of the coherent relationship is a principle of scientific English translation。