This study systematically examines the effects of polyacrylamide (PAM) and polyethylene oxide (PEO) as filter aids on the dewatering performance of limonite ore, and explores their underlying mechanisms of action through comprehensive experimental analysis. The solid-liquid separation behavior was evaluated using bench-scale sedimentation tests, vacuum-assisted dewatering experiments, and pilot-scale plate-and-frame filter press filtration. The samples were comprehensively characterized by Zeta potential analysis, Fourier-transform infrared (FTIR) spectroscopy, laser-diffraction particle-size distribution measurements, and high-resolution scanning electron microscopy (SEM). The results showed that PAM and PEO could reduce the moisture content of filter cake. Under optimal dosage (PAM 20 g/t, PEO 10 g/t) and acidic conditions (pH=2), the filter cake moisture contents decreased to 17.42% and 16.55%, respectively. In addition, under simulated industrial conditions with a filter press pressure of 0.8 MPa, the moisture contents further decreased to 16.85% (PAM) and 15.88% (PEO), which were 0.57 and 1.54 percentage points lower than that of the raw ore, demonstrating a remarkable improvement in dewatering efficiency. Mechanistic analysis revealed that PAM promoted particle flocculation primarily through electrostatic repulsion and adsorption bridging, whereas PEO improved the filtration performance by forming surface complexes and enhancing particle hydrophobicity. These findings indicated that PEO outperformed PAM in limonite dewatering. PEO can not only achieve lower moisture content at lower dosage, but also obtain higher dehydration efficiency and more stable filtration performance. This study provides theoretical basis and technical support for efficient dehydration of limonite. By improving the dehydration efficiency, the research helps to significantly reduce energy consumption and operational costs, while improving the overall production efficiency. The findings lay a foundation for future scientific research and large-scale industrial application of limonite dewatering, and also provide a new way to optimize the beneficiation process.