Sedimentary Formations in Al'Daww Depression has been determined on fossils or strata correlation on upcent of fossils. We found from geological data processing and analysis of litho logical series to Al'Daww Depression that the important rocks that generated oil and gas are belong to Silurian and lower Triassic where as Jurassic sediment does not represent any important, nor upper Cretaceous sediments because its adjacent to surface and invaded by surface water. Reservoir rocks represented by Markada's Kurashina Dolomite, Butma, Rutba and Judea formations. The good cover rocks represented by the Tanf, Amanous Shale and Kurrachina Anhydrite 13 as well as the upcent of some cover formations deteriorated the important of some reservoir formations at Al'Daww Depression This study reveal that the subsiding velocity rate to the basin produced the thickness' and made this formations more prospective in general.