Zero-dimensional lead-halide Cs₄PbBr₆ single crystals have become a research hotspot of novel scintillation materials for radiation-detection applications owing to their high luminescence effciency, large effective atomic number and low-cost solution-processable preparation. In this work,Zero-dimensional lead halide Cs₄PbBr₆ single crystals were grown by a solution-based slow-cooling method and subsequently ground into powder. Composite scintillation films of Cs₄PbBr₆/PMMA with powder loadings ranging from 40 to 90 mg were fabricated using poly(methyl methacrylate) (PMMA) as the polymer matrix. The crystal structure, elemental composition and valence states, film thickness, elemental distribution, and optical properties were systematically characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy, ultraviolet-visible (UV-Vis) absorption spectroscopy, and photoluminescence (PL) spectroscopy. XRD and XPS analyses confirmed that the as-prepared Cs₄PbBr₆ powder crystallizes in the hexagonal space group R3c with high phase purity and the expected chemical states of Cs⁺, Pb²⁺, and Br^-. The composite films exhibited thicknesses of 77.8-124 μm and relatively homogeneous elemental distributions, although mild local agglomeration was observed at intermediate loadings (50-60 mg). All films displayed intense green photoluminescence with a stable emission peak centered near 517 nm. Under irradiation from a ²⁴¹Am α source (5.49 MeV), the α-particle detection performance of the films was evaluated in terms of detection effciency, channel resolution, relative α-response intensity, and scintillation decay kinetics. SRIM simulations indicated that the projected range of the 5.49 MeV α particles in the composite films is approximately 44 μm—well below the measured film thicknesses—ensuring complete energy deposition. All films exhibited a short effective decay constant of approximately 120 ns. Among the series, the film with an 80 mg powder loading delivered the optimal overall performance, achieving a detection effciency of 0.2256, a channel resolution of 0.5628, and a relative α-response intensity of 2.949×10⁶ a.u. (approximately 2-12 times higher than the other loadings). Comparative analysis with previously reported composite α scintillators highlights the advantageous fast timing response of the Cs₄PbBr₆/PMMA system.