Abstract: Whitening the tree trunk has become a necessary means of protecting trees. By whitening the trunk, it can effectively prevent the trunk from being damaged by nature. This paper designs a more adaptable tree trunk whitening device based on SolidWorks, CAD and other software. Through data collection and analysis, the structure size is determined, and the lime water blending and filling structure, portable knapsack whitening machine and other institutions are concentrated on the whole trunk whitening device. Through raspberry PI and power management board, one-way and two-way switches are controlled to realize the control of the whole device. The designed atomized spraying manipulator can wrap the trunk 360° to realize the efficient operation of whitening the trunk. Complete the design of trunk whitening device and portable backpack trunk whitening machine. The design of the tree trunk whitening device and portable knapsack whitening machine aims to overcome the shortcomings of low efficiency, uneven spraying, and poor whitening quality when manually doing trunk whitening work, and realize the use of machine-assisted manual completion of trunk whitening work or the trunk whitening machine to complete the whitening work autonomously. The trunk whitening device has the advantages of exquisite structure, simple operation, low production cost, environmental protection, stability and reliability.