<p>Fiber-reinforced polymer composites (FRPCs) possess outstanding specific strength and specific modulus, making them essential in aerospace, rail transportation, and other advanced engineering applications. However, during the molding process, non-uniform microscopic resin flow through multi-scale fiber networks often induces microscopic defects, significantly reducing the mechanical performance and reliability of the composites. Applying an electric field during molding process has demonstrated substantial advantages in void reduction by promoting uniform resin infiltration and enhancing fiber/resin wettability. Nevertheless, the dynamic resin infiltration processes and flow mechanisms within fiber tows and at single fiber surfaces remain poorly understood. To address this challenge, this study introduces a novel <i>in-situ</i> sensing technique for real-time monitoring of microscopic resin infiltration dynamics under applied electric field conditions. By developing glass fiber sensors coated with Ti₃C₂T_X (MXene) and carbon nanotubes (CNTs), we captured the real-time dynamics of infiltration states within fiber tows and at single fiber surfaces. Analysis of sensing signals confirmed that applied electric field assistance significantly increases resin infiltration velocity and infiltration sufficiency. Multi-scale numerical simulations further elucidated how electric field forces promote resin infiltration into fiber tow pores and improve single fiber surface wettability. As a result, the flexural strength and interlaminar shear strength of the composites increased by 25.5% and 37.3%, respectively. This research provides novel insights into electrically-assisted molding processes by integrating <i>in-situ</i> sensing with multi-scale numerical simulations, addressing a critical need for dynamic monitoring of resin infiltration and multi-scale mechanism analysis.</p>