Based on systematic studies of sedimentology, sedimentary facies, microelements and composition of skeleton granules of sandstone, etc. the authors consider that the Carboniferous System distributed in the Shangcheng-Gushi area, Henan Province and the Meishan Group in Jinzhai County , Anhui Province, which are located at the northside of Dabie Mountains are typical foreland coal-bearing molasse formations. The sedimentary facies are dominated by gravelly braided river-alluvial fan, littoral (non-barrier), tidal flat, freshening lagoon and restricted platform facies. Generally, the Carboniferous is composed of 3 sedimentary cycles. They are in ascending order; Cycle I , the Huayuanqiang Formation (Tournaisian); Cycle n , the Yangshan Formation (Visean) to the middle of Daorenchong Formation (Middle Namurian) ; Cycle 1 , the upper and middle parts of the Daorenchong Formation (Upper Namurian) to the Shuangshitou Formation (Stephanian) , which roughly coincide with the curves of global sea-level changes in the Carboniferous.The Carboniferous - Permian Systems are composed of sediments in continental-marine transitional and littoral environments under a warm and wet climate, and represent the marginal facies of a marine basin. The sediments mainly came from recycled orogens (collision sutures and fold-thrust belts) , belonging to typical deposits of a foreland basin.Studies of sedimentary facies show that in the Carboniferous - Permian the Huainan area, Anhui Province and the Shangcheng -Gushi area, Henan Province and the Jinzhai area, Anhui Province are connected by seawater, i. e. , a unified Carboniferous - Permian back-arc foreland basin was already formed at the part of the present Hefei basin. Its formation shows that in late Early Palaeozoic to early Late Palaeozoic, the Dabie massif (or the northern Dabie Arc) collided with the North China plate and then the two joined into one.