In recent years, metaphor, as a kind of communication between thoughts and a thinking method, has become more and more popular among advertising creators. In the process of creating, we usually apply the use of metaphor rhetoric to make the advertisement full of more profoundly implied meanings and have better publicity effect. Metaphor is a fundamental way of human thinking and cognition. It plays a significant role on our understanding of outside things and ourselves. The study of public service advertising from the perspective of metaphor can provide a new perspective in this field of study. What’s more, the study of public service advertising can improve public service advertising’s cultural taste, promote the propaganda and enhance the aesthetic value.

Although most linguistic scholars in China have many deep researches about metaphor to some degree, the specific studies on conceptual metaphor are still little. Most studies are mainly based on the English corpus, but there are not too many studies based on Chinese corpus. The thesis tries to apply conceptual metaphor into the study of public service advertising and analyze the metaphorical expressions in public service advertising on the basis of the theory of conceptual metaphor. 

2. Literature Review文献综述

2.1 Previous Studies of Public Service Advertising

In western countries, public service advertising is widely used to convey the government awareness, to ease the social psychology and social contradictions. Although public service advertising in China pays an important role in modern society, it cannot cause enough attention of Chinese scholars. Scholars mainly concentrate on commercial advertisements, while the researches on the public service advertising are still relatively little, which can be proved from the small quantities of published works and articles. 

So far there are only four monographs about public service advertising, including Gao Ping’s Of Public Service Advertisements, Pan Zehong’s Public Service Advertising, Ni Ning’s New World of Advertising and Zhang Mingxin’s The Mystery of Public Service Advertising.

Although researches on public service advertising are relatively weak, there are also some theories. They also accumulate and summarize the functions, characteristics, creation, writing style and so on. In addition, more scholars study the commercial advertisements, few scholars study the public service advertising, let alone the metaphorical expressions in the public service advertising. 

2.2 Public Service Advertising

2.2.1 Definition of Public Service Advertising来!自~优尔论-文|网www.youerw.com

Public service advertising, an effective form to advocate social ideas and service for the public, has already penetrated into all aspects of life and is increasingly becoming one of the effective means of reflecting social problems.(Feng,2006:187)

In Chinese advertising dictionary, public service advertising is defined as an advertisement that is created and published by the social public. It is designed for raising awareness of social problems without charge by disseminating some kind of thought. Meanwhile, public service advertising regulates one’s own behavior according to the principle of social welfare in order to advocate certain social cause or social conduct.

Zhang Mingxin defines public service advertising as a kind of advertising campaign which is non-profitable. It spreads beneficial social thoughts so as to change the public’s attitude and behavior through the technique of artistic expression. Public service advertising is more easily accepted by the public because of its lively and short form as well as its various techniques of expression.

In western countries, the main point of public service advertising is determined by social problems. They pay more attention to public’s attitude and behavior, manifesting the problem and subject consciousness. While in China, researches on definition of the public service advertising are still restricted in the level of advertising.