To improve the efficiency and quality of tree trunk liming, while reducing the labor intensity, this article outlines an automatic tree coating machine based on the cooperative functioning of multiple nozzles. This automatic tree coating machine detects the position, diameter, inclination and other parameters of the trunk through the use of an infrared distance meter and ultrasonic distance measuring instrument. This device can control the opening, closing angle, and moving speed of the spraying device through the servo motion mechanism achieving accurate spraying of trees. The results of tree spraying tests indicated that the average spray coverage rate can reach 97.73% in cases where tree trunks circumference are 50-80 cm and inclination angles are between 80-100°. The average spray coverage rate can reach 98.06% when tree trunk circumference is between 80-125 cm and inclination angles are 100-120°, the average spray coverage rate was 81.66% when tree trunks circumference are more than 125cm and inclination angles are 120-140°. The rate of spraying efficiency is 100-120 trees/hour, meeting the whitening requirements of trees and sufficient to replace manual operations.