Spontaneous imbibition-induced reservoir water lock damage is one of the significant factors affecting the production capacity of tight sandstone gas reservoirs. The addition of polymeric surfactants in drilling fluids can alter the wettability of rock surfaces，reduce liquid surface tension，and mitigate reservoir water lock damage. This study synthesized a fluorocarbon-type polymeric surfactant. Through static characterization methods，including infrared spectroscopy，thermogravimetric analysis，and particle size analysis，the study clarified their molecular structures，thermal stability，and particle size distribution characteristics.On this basis，surface tension experiments，gas-liquid-solid three-phase contact angle experiments，spontaneous imbibition experiments，core displacement experiments，and nuclear magnetic resonance（NMR）were employed to investigate its effect and principle in mitigating water lock damage. The results show that the synthesized polymeric surfactant molecules exhibit no weight loss below 200 °C with slow thermal decomposition rates up to 330 °C，demonstrating good thermal stability characterized by a primary decomposition peak at 390 °C. The particles show excellent uniformity with an average size of 53.69 nm，belonging to the nanoscale emulsion category that meets the dimensional requirements for accessing most pore throats in tight sandstone. This polymeric surfactant maintains effective surface tension reduction under high-temperature conditions，with its 1.0% wt aqueous solution exhibiting a surface tension of 41 mN/m at ambient temperature and decreasing to 28 mN/m at elevated temperatures. The contact angle of deionized water on core surfaces increases from 45° to 94°. The capillary force significantly weakens as the contact angle increases，significantly inhibiting the spontaneous imbibition rate of the core. This modification leads to a 61.4% average reduction in spontaneous imbibition rate within the 0-10 minute，with ultimate water saturation decreasing to less than one-third of the original value. When incorporated into simulated drilling fluids at 1.0% concentration，the surfactant substantially reduces liquid phase retention in pores and mitigates water block effects caused by fluid invasion，resulting in improved average core permeability recovery rate from 60% to 86%. The synthesized polymeric surfactant demonstrates dual advantages of excellent thermal stability and nanoscale characteristics，enabling efficient plugging of tight sandstone pore throats. It significantly reduces liquid surface tension while enhancing core contact angles through hydrophobic modification，thereby suppressing spontaneous imbibition rates and improving permeability recovery rates effectively. By regulating wettability，reducing capillary forces，and enhancing fluid flowback capacity，the polymeric surfactant mitigates water block damage，providing key technical support for optimizing hightemperature reservoir drilling fluids.