From the Later Sinian to the Middle Triassic, 3 series of marine source rocks were deposited, i. e. , the Upper Sinian-Upper Ordovician, Carboniferous-Permian and Lower Triassic in the Jiangsu, Zhejiang and Anhui Provinces. The three hydrocarbon source rocks have different characters of thermal evolution: The Lower Palaeozoic source rocks have undergone structural deformation by the Caledonian and Indosinian-Yanshanian movements, and now at an over-mature dry gas stage; the Upper Palaeozoic source rocks are basically in the late period of oil generation. The great part of the Triassic source rocks is in a mature stage, and only a small part is in an unmature stage. The Lower palaeozoic source rocks in the area have experienced two processes of oil generation. The first was in the basin subsidence stage that was prior to the Caledonian movement. The second took place in the marginal sea deposition stage after the Caledonian movement. Thereservoiring and capping conditions are favourable for marine oil and gas generation. It has been proved through years of oil and gas exploration that oil and gas exploration of the Lower Palaeozoic should be based in the northern Jiangsu area, while for the Upper Palaeozoic, southern Anhui and western Zhejiang should also be considered besides the northern Jiangsu area. The exploration of Mesozoic oil and gas should be focused on some well-developed Mesozoic basins, such as Changzhou, Jurong, Wuwei and Wangjiang.