Abstract: Based on the theory of subcategorization in cognitive linguistics, this article mainly deals with the cognitive function and characteristics of premodifiers and postmodifiers in English noun phrases.This article points out that the function of modifiers in English noun phrases is to subcategorize what the head word refers to, that is, what the head word refers to can be classified into two or even more than two subcategories from different angles.The subcategorization of premodifiers is on the basis of the cognitive characteristics of permanence and, generally speaking, postmodifiers subcategorize the head word of special context temporarily.