Acknowledgements I would like to express my sincere gratitude to those who have offered their precious assistance in pletion of this thesis and those who have helped me during my three years’ postgraduate study in the South-Central University for Nationalities. First, I would like to express my greatest thanks to my supervisor Professor Lv Wanying for her prudent instruction and patient revision. She has provided me with the most insightful suggestions and ments. During my postgraduate study, her earnest attitudes and preciseness to academic researches have set a standard for me to follow. I am also grateful to all other professors in the foreign language college of the South-Central University for Nationalities. They have provide me with great inspiration to pursue my academic study. Their profound knowledge and valuable instructions have benefited me. Last but not least, I would like to show my appreciation to my beloved family who always support me. Thanks also go to my classmates and friends who have offered their help and support to me in various ways. Abstract Nowadays, more and more attention has been put on the research of public service advertisement(PSA), especially from the perspective of linguistics. This is due to the continuous development of public service advertisement and linguistics and the important role of public service advertisement in our daily lives. For a long time, the studies on metaphor have been traditionally confined in the field of rhetoric. The publication of Lakoff and Johnson’s Metaphors We Live By marks the establishment of the cognitive approach to metaphor, which is recognized as a great breakthrough in the process of metaphor study. Lakoff and Johnson contend that metaphor is a kind of cognition. The nature of metaphor is conceptual and conceptual metaphor is the systematic mapping between a concrete domain and an abstract domain. In everyday life, people tend to use the concrete and given information as the source domain