Abstract: The dynamic behavior of objects entering water involves complex processes of multiphase flow coupling and interfacial energy dissipation, holding significant application value in military equipment, marine engineering, and biomimetic robotics. In real marine environments, the presence of heterogeneous medium layers (e.g., oil films) necessitates consideration of air-oil-water three-phase coupling effects for water entry problems, with dynamic characteristics differing markedly from traditional air-water two-phase systems. To investigate the regulatory mechanisms of the viscous oil film on the motion resistance, cavity evolution, and closure characteristics of hydrophobic spheres during water entry, thereby providing theoretical support for water entry problems in complex media environments, this study employed a combination of high-speed photographic experiments and theoretical modeling. It comparatively analyzed the dynamic differences between hydrophobic