苏北盆地古生界海相层系发育有5套良好的烃源岩，其累计厚度大，有机质丰度高。研究表明：晚古生代—三叠纪期间，苏北盆地属于下扬子陆表海沉积，构造活动稳定，沉积速率小，古生界烃源岩得到了很好的保存；燕山运动早期由于推覆倒转和岩浆活动导致古生界烃源岩成熟度在局部地区异常高，但范围有限；晚白垩世晚期—渐新世的断陷和新近纪的拗陷沉积使中生界、古生界顶面埋藏深度渐次达到3 000~5 000 m，烃源岩逐渐进入二次生烃过程，大部分地区进入了高成熟演化阶段。在前人研究的基础上，分析了苏北盆地古生界海相层系晚期生烃、晚期成藏、储盖条件等3个关键因素，指出了该盆地天然气勘探的有利地区。

Five Palaeozoic marine source rock sequences, with large total thickness and abundant organic matter, are developed in the Subei basin. Research shows, the hydrocarbon generating potential of Palaeozoic source rocks have been preserved because of stable tectonic movement and low depositional rate in the basin which belongs to epicontinental sea sediments from late Paleozoic to Triassic. During the early Yanshan Movement, overthrusts and magmatic actions led to exceptional high evolution degree of source rocks in limited areas of the basin. The burial depth of the top Mesozoic and Paleozoic gradually gets close to 3 000~5 000m, which was caused by the fault depressions in the late period of Late Crataceous-Oligocene Epoch and the Neogene depression depositions. The source rocks started the secondary hydrocarbon generation and reached high evolution degree in most areas of the Subei basin. Based on the comprehensive evaluation of late hydrocarbon generation, late hydrocarbon accumulation, and reservoir seal conditions, this paper points out the favorable gas exploration zones in the Subei basin.