Spring continually is the working way of traditional orchard spring machine.Large gap exist in small orchard trees and the trees are sparse.Spring in the gap not only waste of pesticide,but also pollution the environment.This paper design the control system based on target laser detection,which fix on the 3WGF-300C air-assisted spring machine.Through 3 laser sensors,the PLC can control the solenoid valves in the system.The laser beam is very fine and the size about 15mm×15mm,this defect will lead solenoid valve open many times when the laser sensor scan one orchard tree that include many leaves.The paper use the computer program way of or on 3 laser sensors,means linear spring that when 1 or more laser sensor detect a orchard tree,all solenoid valves will be trigger.In the condition of orchard trees distance 1.5m and spring pressure 0.1Mpa and velocity of spring machine 0.4m/s,the volume of application are: spring continually 11.8L,and one laser sensor control one solenoid valve 2.9L,and linear spring 4.4L,the frequency of solenoid valves working are:one laser sensor control one solenoid valve 44,57,40 times(up to the down),and linear spring 20 times.The result shows,the way of one laser sensor control one solenoid valve can save pesticide 75%,but the large working times of solenoid valves will lead the error of the control system.Linear spring not only save pesticide 65%,but also decrease the working times of solenoid valves,it can be put in application.