“Deep eutectic solvent (DES) + surfactant” improved water flooding is a new technology proposed in recent years to enhance oil recovery with low cost and environmental protection. Based on microfluidic technology, combined with related properties characterization and microscopic oil displacement experiments, the microscopic oil displacement mechanism of choline chloride: urea (1:2) + cetyltrimethylammonium bromide (CTAB) system in medium and high permeability reservoirs is a study in this paper. Through the viscosity, wettability, and interfacial tension tests, it is found that the system can increase the displacement phase viscosity, reduce the mobility ratio, increase the sweep efficiency, improve the rock wettability, promote the rock surface to change to the water-wet direction, and significantly reduce the surface tension between oil and water. Through the microscopic oil displacement experiment, the system can improve the oil displacement efficiency to a certain extent in the single orifice throat model. The process of residual oil droplet migration, residual oil film stripping, and large amounts of residual oil utilization under the system’s action after water flooding is shown in the glass etching model, and the microscopic oil displacement mechanism is initially defined. This study can provide theoretical support for the applicability and field application of the improved water drive system in medium and high-permeability reservoirs.