Abstract: After introducing natural semantic metalanguage theory（NSMT）briefly，this paper expatiates on its rationality from the persperctive of cognitive linguistics and the inspiration from it for teaching English as a second language（TESL），which is a process of constructing the English langauge linguistic system.NSMT tries to deconstruct a langauge system depending on numbered semantic primitives.If this process of deconstructing is understood，there is possibility to make clear the relationship（motivation）between the linguistic forms，notions and contents，which makes NSMT unreplaceable in guiding TESL.Linguistic theory supporting a language teaching method and the method itself should reflect the influence of the outsideworld，hunman beinings cognition and social culture on language，and must tally with the cognitive mentality that accompanies the emergence，development，formation and use of a language.Nowadays，NSMT and the teaching methods deriving from it are qualified to act such a role.