Fluidity is a critical property of cement that significantly impacts the performance of cement paste in construction engineering. Fluidity is typically enhanced through the application of chemical additives (e.g., water-reducing agents). While chemical additives can enhance the fluidity and workability of cement, their drawbacks, such as cost and environmental impact, must be carefully considered. Most of the current research focuses on the use of chemical admixtures, while studies on physical alternatives remain limited. This study employs molecular dynamics (MD) simulation to propose an innovative strategy for improving the fluidity of cement slurry by applying an electric field, which acts as a physical water reducer. This research investigates the lubricating effect and underlying mechanism of the electric field on cement hydration product C–S–H particles at the nanoscale. This work demonstrates that increasing the electric field strength significantly reduces friction between cement particles, thereby improving fluidity when ions are present at the particle interface. Atomic-level structural analyses reveal that the electric field promotes a denser C–S–H structure and facilitates ion desorption from the C–S–H surface, which acts as a lubricant between particles. This study provides new insights into how an electric field can serve as a lubricant in cement systems, offering a promising approach to enhancing concrete fluidity without relying on chemical admixtures.