Abstract: Tetracycline (TC), a typical broad-spectrum antibiotic, is widely distributed in multiple environmental media and poses serious risks to ecological safety and human health. Restricted by conventional water treatment processes, tetracycline residues persist in various aquatic environments, thereby creating an urgent demand for efficient water pollution remediation technologies. Membrane separation technology has emerged as a research hotspot for antibiotics removal in aqueous solutions owing to its superior separation performance, and poly(vinylidene fluoride) (PVDF) has become one of the most commonly used substrate materials in this field. Nevertheless, pristine PVDF membranes suffer from poor hydrophilicity, low contaminant removal capacity and inferior antifouling performance. In this study, utilizing the tunable ionic characteristics of ionic liquids and the structural stability of polymers, poly(1-hexyl-3-vinylimidazolium bromide)-poly(vinylidene fluoride) composite membranes(PILMs) were prepared via blending modification. A pressure-driven membrane filtration system was constructed, and a novel approach for the removal, enrichment and determination of tetracycline in water was developed in combination with high-performance liquid chromatography (HPLC). Scanning electron microscopy (SEM), energy-dispersive spectroscopy mapping (EDS-mapping) and Fourier transform infrared spectroscopy (FTIR) were applied to characterize the micromorphology, elemental distribution and chemical structure of the as-prepared membranes. Key properties including hydrophilicity, pore structure, surface charge and thermal stability were systematically evaluated. The preparation parameters were optimized, and the optimal conditions were determined: poly(ionic liquid) dosage of 0.30 g and casting solution volume of 3.0 mL. The influencing factors on removal efficiency were further investigated, and the optimal operating conditions were confirmed: room temperature, a pump speed of 4 r/min, an injection volume of 40.0 mL, an initial concentration of 6.0 μg/mL, and a solution pH of 7.00. Under the optimal conditions, the tetracycline removal efficiency of PILMs reached 87.0%. The separation mechanism of tetracycline by the composite membrane was dominated by physical adsorption, following a heterogeneous multilayer adsorption model. Van der Waals forces acted as the major driving force, accompanied by electrostatic interactions. The composite membrane exhibited a tunable structure, satisfactory thermal stability and favorable mechanical properties. Meanwhile, the membrane separation process remains efficient, eco-friendly, easy to operate, demonstrating promising industrial application prospects.