<p>The dolomite reservoirs in the Fourth Member of Ordovician Majiagou Formation in the central-eastern Ordos Basin serve as important targets for deep carbonate oil and gas exploration in the basin. Clarifying the reservoir characteristics and main controlling factors is of great significance for improving oil and gas exploration efficiency and deployment. This study is based on various geological data including core observation, thin section analysis, X-ray diffraction, and carbon-oxygen-strontium isotope analysis from Well Xiaohao-1. The petrological characteristics, reservoir space types, and reservoir physical properties of the dolomite in this interval were systematically analyzed. The influences of main controlling factors including sedimentary environment, bioturbation, dolomitization, and early diagenetic karstification on reservoir formation were discussed. Research results show that the dolomite reservoirs in the Fourth Member of Majiagou Formation are mainly characterized by intercrystalline pores, intracrystalline pores, and structural fractures as the primary reservoir spaces, exhibiting a pore-fracture composite reservoir structure. The reservoirs generally display tight to low-porosity and low-permeability characteristics, but areas with well-developed coarse-crystalline dolomite locally possess good reservoir properties. The sedimentary environment controlled the formation of favorable microfacies, providing the material foundation for reservoir development. Bioturbation promoted dolomitization and pore preservation. Dolomitization not only enhanced pore structure but also improved pore stability and connectivity. Early diagenetic karstification further enlarged and modified the original pores. The superimposed coupling effects of the above factors jointly controlled the spatial distribution and quality differences of dolomite reservoirs in this area.</p>