Based on a discussion of tectonic evolution and forming rules of hydrocarbon reservoirs,the paper thought that the Lianyuan Depression experienced two main stages of tectonic evolution: the marine sedimentary cover depositing from Middle Devonian to Early Triassic, and the continental facies sediments depositing from Middle Triassic. The existed thrust structures and the tectonic framework created in the Indosinian orogeny and fell its pattern in the Yanshanian orogeny. It was also suggested that there were two stages of forming of hydrocarbon reservoirs: the earlier hydrocarbon reservoirs were mainly oil ones which formed in the Indosinian cycle and turned into gas reservoirs in the Early Yanshanian period,then,the reservoirs reformed and became the secondary gas reservoirs in the Middle Yanshanian period. The later hydrocarbon reservoirs were oil and gas ones originally, which formed after the main episode of Yanshanian orogeny. The paper forecasted that the secondary gas reservoirs would be found in anticlines of the central syncline belt and the original oil and gas reservoirs found in buried sub-anticlines of the central syncline belt.