Aiming to solve the problem that the spray boom sprayer needs to be installed with auxiliary devices such as grain distributor when it is used to apply pesticide in the middle and later period of crop growth, and vertical folding sprayer is easy to cause interference, a wide horizontal folding spray boom based on 3WF-1000 spray boom sprayer was designed. The horizontal deployment mechanism and the angular velocity of the spray boom were optimized by using analytic method and genetic algorithm to realize the smooth horizontal deployment and folding movement. A method to adjust the spray boom by the eccentric conical hinge was presented. The angle of spray boom can reach 6.5° by adjusting the angle of the conical hinge pin and the friction torque of the match surfaces. The pressure range of the spring press and the structural parameters of the clutch were determined by mechanical analysis. The dynamic transfer function mathematical model was established, and the adaptive suspension spring stiffness coefficient was 1500N/m and the damping coefficient of the damping plate was 3500N·s/m. The static and dynamic characteristics of the spray boom and its key components were simulated. The results of the static and kinematic simulation of the spray boom showed that the structure parameters of the spray boom were reasonable, and the stability and deployment fluency met the design requirements. Ground test showed that the deployment process of the horizontal foldable spray boom was stable and had no stagnation, and the eccentric conical leveling mechanism can correct the tilt of the spray boom effectively. In the field test, the average degree of droplet deposition was 27.1/cm2, and the variation coefficient of spray distribution along the direction of spray boom was 5.1%.