Abstract: To address operational management and performance evaluation challenges in low-altitude logistics transportation, this paper designs a digital twin-based multimodal low-altitude logistics distribution system. Adopting a three-tier architecture comprising physical systems, simulation engines, and information systems. The simulation engine layer leverages Unity3D to build a 3D simulation environment scaled to match the physical world, achieving visualization of transportation processes and behavioral reproduction. The information system layer integrates a vehicle-drone collaborative delivery scheduling model. Aiming to minimize total delivery costs, it employs a hybrid particle swarm algorithm incorporating large neighborhood search to solve scheduling problems. This is combined with an improved artificial potential field method for drone route planning. The simulation engine layer simulates the scheduled plans and drone trajectories. Based on simulation results, the logistics system's operational processes are analyzed, and feasible solutions are subsequently applied to the physical system layer. A digital-twin implementation for an office-campus scenario demonstrates efficient vehicle-drone coordination and safe, feasible drone trajectories, thereby validating the effectiveness of the proposed system.