There are different strategies in explaining propositional attitude ascriptions in the literature of philosophy of language and mind. We point out the difficulties of both camps,i.e.direct reference theory and neo-Freageanism,in understanding the relationship between the sense and the semantic content of a sentence. Based on the four-level framework of theory of reference,we analyze the structure and the necessary conditions of a successful referential communication. Then we suggest an "expression-communication principle based on presupposition" to deal with the semantic content of a sentence,which might be taken as a modification of J.Stanley’s recent work. Finally we suggest a way out of Kripke’s puzzle about belief in terms of the new model of referential communication.