Abstract: Interrogative pronouns which take interrogative meaning as the core category are the natural focus of sentences. Having an important position in both Chinese and English languages, the interrogative pronouns are often expanded in usage. In order to meet the needs of communication, the semantic domain of interrogative pronouns can be expanded to the non-interrogative category, which include universal reference, indefinite reference, exclamation and negation. This phenomenon exists across languages, showing it is not accidental, whereas it is inextricably linked with the common cognitive law of human being. Furthermore, resulting from their syntactic positions as the interrogative focus, the interrogative pronouns of Chinese and English also have derivational functions of introducing a clause or anaphora usage respectively.