In response to the challenges encountered in the Jiyuan region of the Ordos Basin, which encompass high water injection pressure, constrained water flooding volumes, and a subdued oil recovery rate in ultra-low permeability reservoirs, an exhaustive study was initiated. This investigation concentrated on assessing the interfacial activity, emulsifying capability, and wettability alteration potential of bio-nano surfactants, specifically stearic acid amides. Comprehensive oil displacement experiments were conducted using various reservoir cores. The primary objective of this investigation was to explore and develop surface active agent flooding techniques that could potentially augment water flooding volume and enhance oil recovery in ultra-low permeability reservoirs. The experimental results show that: ① The biological nano active agent (ZS-1) effectively reduces the oil–water interfacial tension within a concentration range of 0.2–0.3%, achieving magnitudes of 10–3 mN/m, altering the emulsification characteristics of crude oil, and modifying the wettability of the formation pore surfaces, resulting in a stable oil–water emulsion. ② The surfactant demonstrates robust tolerance to emulsions under extreme acidic or alkaline conditions, as well as in high salinity environments. Optimal stability is observed within a temperature range of 65–75 °C. ③ Given the narrow pore throats of ultra-low permeability oil reservoirs, the implementation of surfactant flooding leads to effective emulsification and oil washing, accompanied by a significant pressure drop. Notably, there is enhanced adaptability to cores with very poor permeability of 2.0 and 4.3, increasing the recovery rate by 3.6–4.8%. Through an exhaustive series of experiments, the effects of various factors on the surfactant oil displacement efficiency were elucidated, along with the synergistic interactions between wettability and emulsifying properties. Furthermore, the migration and sealing behaviors of the surfactant during displacement processes in heterogeneous cores were revealed, providing theoretical support for the development of innovative surfactant displacement technologies for such reservoirs in later stages.