This article aims at the fundamental problem in the Study of Gongdiao (the gong tune) on which diverse arguments accumulated from the Ming dynasty (1368-1644) up to this day, namely the gap in both theory and practice caused by the form of biaodiao (marking tunes) changing from yuese biaodiao to dise biaodiao during the early Ming. Taking southern and northern formularies of lyric as the first hand material, basing on the Gongdiao theory in ciyuan jianjian, this article discusses and determines 1) the Gongdiao system of the southern and northern music tunes was an inheritance of the suitang yanyue ershi ba diao (Twenty-Eight Tunes of the Sui and Tang Popular Music); 2) dise biaodiao of the southern and northern music tunes was evolved from the yuese biaodiao in the popular music tunes; 3) the settling-tune flute used in the southern and northern music tunes was a continuation of the music instruments applied for settling tune and regulating pitch in suitang yanyue diao (popular music tunes of the Sui and Tang). These three important issues addressed here are to lay basic foundations for further research into the historical facets of Gongdiao in the southern and northern music tunes.