To improve the mechanization of plant protection in the orchard, the plan of the orchard sprayer chassis was determined on the basis of the investigation.Combining the production status of agriculture vehicle, unmodified chassis was selected.The layout scheme of postposition fan and special-shaped agrochemical box was adopted.The power system was redistributed by the transfer case and the force taking device.The research filled the blank of sprayer chassis systems for density orchard in china.The vehicles performance of through and dynamic were well.