Abstract: Tautologies are ubiquitous and attracting attention from a wide range of disciplines. This seemingly meaningless construction can be used to convey a variety of pragmatic meanings which can be properly explained by neo-cognitive pragmatics, a theoretical model integrating insights from both relevance theory and cognitive linguistics. The comprehension of tautology, just like the comprehension of any other linguistic expressions or ostensive stimulus in general, is guided by the pursuit of optimal relevance. It is argued in this paper that through the marked construction of tautology, addresser intends to invoke some contextual effects in addressee, including strengthening, contradicting or partially contradicting contextual consumptions. And this process can be more specifically characterized by the notion of cognitive model in cognitive linguistics. It is also proposed that the main motivation of using tautology lies in its capability of cultivating intimacy between addresser and addressee.