Aiming to address the issue of crop damage caused by the strong downwash airflow from the rotors during the operation of heavy-load agricultural drones, which leads to increased flight altitude and intensified droplet drift, a turbulence device that can effectively reduce the downwash airflow velocity was designed. Based on the self-developed unmanned aerial vehicle ( UAV) in the laboratory as the test platform, combined with the self-developed wind speed sensor and computational fluid dynamics (CFD) simulation technology, the weakening effect of the flow deflector on the wind field under different structural parameters was quantitatively tested and analyzed. The optimal parameter combination of the turbulence device was determined, effectively verifying its engineering feasibility and technical advantages in weakening the rotor downwash airflow. The research results can provide theoretical support and experimental basis for the practical application of the turbulence device on heavy-load agricultural UAVs, and a scientific and feasible technical solution for parameter matching and selection was formulated. Firstly, the key parameter types of the turbulence device were screened and determined based on its working principle, together with basic physical models including aerodynamics, momentum theory, and Newton??s third law. Secondly, according to the trajectory line cloud map and velocity cloud map of the downwash wind field under the working state of the UAV, the gradient change range of each parameter variable was reasonably clarified. Then through the combination of CFD simulation and orthogonal experiments, the optimal values of each parameter were comprehensively analyzed and optimized. Subsequently, by combining CFD simulation and orthogonal experiments, a multi-variable coupling analysis and optimization design of each key parameter was conducted, and the optimal parameter combination was obtained. Finally, the stability and effectiveness of the turbulence device were verified through on-board flight tests. The results of the orthogonal experiments showed that the ratio of the wind field optimization effect to the thrust loss rate after installing the turbulence device was approximately 9.7, indicating that the device effectively weakened the downwash airflow while having a relatively small impact on lift performance. Flight tests showed that after installing the flow deflector, the thrust of the UAV was increased by approximately 10.8% , and the average wind speed of the wind field was decreased by approximately 38.6% , demonstrating a good wind field optimization effect. Moreover, the UAV with the turbulence device installed flies stably and had good compatibility with the flight control system of the UAV, fully meeting the overall design requirements of agricultural operation.