The traditional axial-flow air-assisted orchard sprayer is lack of guidance for air-assisted spraying, which would lead to the waste of pesticide. The 3WZF-400A orchard air-assisted sprayer uses two linear guide plates to guide its air-velocity field, which could partly solve the problem, but it still could not make the distribution of air-velocity match the canopy shape at the target. To this matter, the air-velocity field distribution model was established by CFD simulation, and the optimized angle was selected with combination of the two linear guide plates as the basis for the further improvement. Short guide plates with different angles and quantities were set up to subdivide the air-velocity field above. Proper combination of the two linear guide plates could make the airflow concentrate to the canopy range, the optimized angle are 45° for the upper and 5°for the lower. Short guide plates could effectively subdivide the air-velocity field, and could concentrate the airflow to the target. But too many short guide plates would lead to the interference of airflow. The optimized quantities and angels for short guide plates are 2, 15° and -15°. The experimental verification and spray performance test were carried out. The maximum relative error between analog value and measured value was 22.87%, which caused by the attenuation of the air-velocity and the instability of the airflow source. The droplet coverage rate was used to evaluate the spray performance of the improved air-assisted sprayer, the comparison experiment between previous sprayer and the improved sprayer showed that the droplets could be reasonably distributed according to the canopy shape in the vertical plane.