McLuhan(1967) has ever said: 「Advertising is the greatest form of art in contemporary.」 Actually, Advertising is not only an art of persuasion, but also a very unique language communication form. From the point of view of Pragmatics, advertising is a kind of pragmatic behavior, its main purpose is to change the attitude and behavior of consumer, and then take the advantageous action toward the product or brand。Pragmatic presupposition is the proposition that has presupposed without need to say or write when we are talking or writing, and it is omnipresent in our daily conversation or communication. This paper addresses the psychology function and characteristics of presupposition and explores its application and effect on advertising copy. Through the research of application of pragmatic psychology in advertising copy, how the communication works through the advertising language is explored , and it helps the effective copywriting and grasps the skill of how to seduce consumers through copy.