Asmari Formation of Q oilfield in the Middle East is widely developed mixed siliciclastic-carbonate sediment. Through core observation, microscopic thin section and other data, combined with the study of sedimentary system, the mixed sediments characteristics and reservoir development model of Asmari Formation were studied in detail. The study shows that Asmari Formation in Q Oilfield develops the sequence mixing of clastic rocks and carbonate rocks, also develops the structural constituent mixing of terrigenous clastic and carbonate components. The mixed sedimentary rock types in the study area are rich and diverse, including clastic rocks, carbonate rocks and mixosedimentite composed of terrigenous debris and carbonate components. There are three types of mixosedimentite reservoir development models in the study area, which can be further subdivided into nine sub-categories, and the development models and distribution characteristics of different types of mixosedimentite reservoirs are summarized. The research results provide an important geological basis for the fine development of oilfields such as well location deployment and horizontal well target design.