摘要
This paper applies prototype theory to explain the motivation of polysemy. There are mainly 3 types of meaning model of polysemy, namely, radiation, concatenation and integrated model. According to prototype theory, in the semantic category formed by a polysemic word, category members are determined by prototype. They are the result of development from prototype to boundary. Connected by a network of overlapping similarities （i.e., family resemblances）, category members present different degrees of prototypicality, but not all of them can represent the category. Only the prototype can fully embody the category. With the extension of the semantic category, the boundary of the category is fuzzy and begins to intersect another semantic category.
