Abstract: The Delingha Fault-depression in the north margin of the Qaidam Basin is a frontier of petroleum exploration.Combining the field petroleum geologic review on the outcrops with the well and seismic information,the mudstone,carbonate rock and coal-measure hydrocarbon source rocks in the Mesozoic Jurassic and Paleozoic Carboniferous are considered widely developing in the Delingha Fault-Depression.The mudstone and carbonate rock in the Ordovician are also good hydrocarbon source rocks.The sandstone reservoirs developed in both the Mesozoic and the Cenozoic.The Delingha Fault-Depression is of two segs mingle with one uplift in structural framework.In the Delingha Fault-Depression,the tectonics developed and the traps are characterized by various types,large quantities and area as well as burial depth less than 4 000 meters.These are favorable for drilling.The total forecasting oil/gas reserve in this area is above 10 million tons.It is a favorable area for oil and gas exploration,and has well exploration prospect.