本文從現代北京話、《切韻》音系和由中古至現代所產生的語音變化中歸納出介音與其他語音成分之間所存在的排斥律與和諧律，從中探測其語音學上的根據和歷史上的成因。實際上，與介音有密切關係的是聲母和韻尾，主要元音和聲調很少與介音發生特殊現象。

　　In this paper, the author induces exclusive rules and harmony rules between medial onglides and the other phonological elements as revealed in Modern Pekinese, Middle Chinese and the phonological changes from Middle Chinese to Modern Pekinese. Moreover, the paper surmises the phonetical reasons and the historical causes of these relationships. As a matter of fact, only initial consonants and ending consonants/vowels have close relationships with medial onglides, while principal vowels and tones rarely have special relationships with them.

現代北京話; 《切韻》; 近代音

modern Pekinese; Ts’ieyun; old Mandarin