Abstract: The low-altitude economy has been established as a national strategic emerging industry. The explosive development of Unmanned Aerial Vehicles (UAVs) and Electric Vertical Take-off and Landing (eVTOL) aircraft poses stringent requirements for materials to be "lightweight, low-cost, and sustainable." By virtue of their high specific strength, excellent vibration damping properties, and green low-carbon attributes, as well as advantages such as low cost, green manufacturing, and waste recyclability, plant-based composites have become a critical pathway to breaking through the material bottlenecks of low-altitude aircraft. This paper systematically reviews the constituent systems of plant-based composites (plant fiber/bio-based resins) and provides an in-depth analysis of key technologies, including raw material pretreatment (physical/chemical/biological modification), interface compatibility optimization mechanisms, and advanced manufacturing processes tailored for aircraft components (e.g., resin transfer molding, 3D printing). On this basis, the application progress in primary load-bearing structures (fuselage, wings, and empennage), propulsion systems, and functional components (protective covers, radomes, and interiors) of low-altitude aircraft is comprehensively surveyed. Although plant-based composites hold huge application potential, challenges such as weak interfacial bonding, poor stability in hydrothermal environments, insufficient flame retardancy, and absence of airworthiness certification remain severe. Finally, the article prospects future development directions from the aspects of high-performance hybrid structural design, digital manufacturing and standardization system construction, and full lifecycle green management, providing a reference for promoting the large-scale application of plant-based composites in the low-altitude economy.