Abstract: To enhance the viscosity of the displacement phase and reduce the viscosity of heavy oil, a viscous and microdynamic emulsifying binary oil displacement agent was developed. This system is formulated by mixing the temperature-tolerant and salt-resistant polymer BM with nonionic surfactant AC1205, which integrates dual functions of increasing viscosity of aqueous solutions and reducing viscosity of heavy oil through microdynamic emulsification. The influence of system composition on solution properties was systematically evaluated, and both macroscopic and microscopic oil displacement efficiencies were analyzed. Results show that AC1205 has a minor impact on the viscosity of BM solutions. When the mass fraction of AC1205 ranges from 0.2% to 0.3% and the oil–water ratio varies from 1∶9 to 5∶5, the BM/AC1205 mixed system can effectively emulsify heavy oil under microdynamic conditions. Accordingly, the viscosity of the oil displacement agent can be flexibly adjusted based on the mass fraction–viscosity relationship of BM. Leveraging these characteristics, the system simultaneously modulates oil and water phase viscosities through the synergistic effect of polymer-induced viscosity enhancement and surfactant emulsification-induced viscosity reduction, thereby significantly lowering the water–oil mobility ratio. Core flooding experiments further verify that this viscous and microdynamic emulsification system enhances heavy oil recovery by 18.7 percentage points compared with conventional water flooding. The research results have provided a new technical approach for the efficient development of heavy oil reservoirs.