Objective Since 2019， CNPC has conducted exploration on the Upper Cretaceous Donga strata in the Trakes slope of the Termit Basin， Niger. Several wells obtained industrial oil flows， demonstrating good exploration potential. Compared to the Paleogene fluvial-deltaic Sokor1 Formation， the detailed characteristics of the Upper Cretaceous marine sandstones of the Donga Formation have not yet been fully examined. Methods In the present study， based on seismic， wireline， and mud logging data， 53 side wall cores and cutting samples from four wells were analyzed with thin sections， casting thin sections， X-ray diffraction， scanning electron microscopy， gamma-ray spectral logging， etc. Therefore， this study investigated the marine sandstone reservoir characteristics of DS1 member and DS3 member in the Donga Formation and analyzed their controlling factors. Results The results show that the rock type of the DS1 member is mainly fine-medium grained quartz sandstone with high component maturity， whereas the DS3 member is dominated by fine grained lithic quartz sandstone with mass calcareous mineral cement. The reservoir rock quartz grain is sub-round to round with moderate to poor sorting in the Donga Formation， the rock matrix is mainly composed of kaolinite and calcite， and most of quartz grains have point to line contact. Reservoir rock diagenesis have strong compaction and cementation， with common dissolution， and the pores are primarily intergranular with medium to ultra-low porosity and permeability. The high quality reservoirs in the Donga Formation are mainly distributed in the DS1 member， and reservoir physical property improves from west to east in Trakes slope. The analysis results show that the development of marine quartz sandstone in the Donga Formation is controlled by three factors. Firstly， vertical distribution of the sedimentary face and marine quartz sandstone was controlled by sea level changes， which manifested widespread marine distributary channel sandstones in the DS1 member that deposited in the early stage of marine transgression， whereas the DS3 member， in the highest sea level of marine deposit with high salinity， formed high contents of carbonate cement and poor reservoir physical property. Secondly， the stable gentle slope geomorphology in the Late Cretaceous was favorable for the development of marine sand bodies， and the intense strike-slip fault activities in the Paleogene induced the formation of micro-fractures in reservoir rock， which effectively improved the reservoir physical properties. Thirdly， the rigid construction of marine quartz sandstone granules was favorable for the preservation of rock primary pores， and the dissolution of unstable minerals such as feldspar and calcareous minerals improved the pore structure of the reservoir rock. Conclusions The development of a regional cap rock of marine mudstone and shale was conducive to the formation of self-generation and self-preservation reservoir in the Donga Formation. Compared with the lower slope zone of the Trakes slope， marine quartz sandstone has better reservoir physical properties and widespread distribution in the middle and high slope zones closer to the eastern sediment source area and are favorable for further exploration in the Donga Formation.