【Abstract】According to ecological linguistics, lexical cohesion, as an ecological factor of an English text, is helpful to make up a balanced ecological environment of a text. Therefore, in English writing teaching, students should know about different patterns and functions of lexical cohesion, and be guided how to apply different lexical cohesive devices to improve their writing ability as well.
　　【Key words】ecological linguistics; lexical cohesion; apply; English writing
　　1. Theoretical Foundation
　　1.1 Ecological linguistics
　　Ecological linguistics is a study of the interaction of language and its survival environment, of which research paradigm covers three main factors including groups, educational activities and the ecological environment in which education activities are carried out in the ecological system of linguistics, and their mutual relations. Under the guidance of ecological linguistics, English teaching is a kind of micro-ecosystem that is a unity of the interaction and energy exchange of teaching environment and internal factors such as teachers, learners, teaching contents, methods, and evaluation etc.
　　Ecological application of lexical cohesion in this paper indicates that lexical cohesion, as an ecological factor consisting of an English text, makes the text balanced by its various lexical cohesive devices.
　　1.2 Lexical Cohesion
　　Mainly based on the most influential Halliday