Abstract: The authors of this paper briefly describe the formative conditions of the Yakela Oil/Gas Field in the following aspects: oil generation, reservoirs, caps, traps, migration and preservation. Emphasis are laid on the analysis of main controlling factors, such as reservoirs and traps in oil/gas fields. It is concluded that the best formative condition of oil/gas pools is the presence of ancient remanent hills in the basin,which consist of Lower Ordovician and its underlying systems, and are directly draped with Triassic and Jurassic systems. Finally, it is suggested that this oil/gas field is a layer-block type of oil/gas pools controlled by lithology,in which the main body of reservoir space consists of a net of linked pores,caves and fractures surrounded by side water and bottom water.