Abstract: To address issues of operations management and performance evaluation in low-altitude logistics transportation, this paper designs a digital twin-based multi-modal low-altitude logistics delivery system. The proposed system adopts a three-layer architecture consisting of a physical system layer, a simulation engine layer, and an information system layer, enabling visual analysis and operational cost estimation of the designed logistics system. The simulation engine layer adopts Unity3D to build a 3D virtual environment with the same scale as the physical world, achieving visualization of transportation processes and reproduction of logistics behaviors. The information system layer integrates a vehicle-drone collaborative delivery scheduling model. With the objective of minimizing total delivery cost, a hybrid particle swarm optimization algorithm incorporating large neighborhood search is developed to solve the scheduling problem. An improved artificial potential field method is also integrated for drone route planning. The simulation engine layer simulates the scheduling plans and drone trajectories. Based on the simulation results, the operational processes of the logistics system are analyzed, and feasible solutions are subsequently applied to the physical system layer. A digital-twin implementation is conducted for a logistics scenario in an office campus. Results demonstrate that the proposed system can provide efficient vehicle-drone coordination, with safe and feasible drone trajectory plans, verifying the effectiveness of the proposed system.