In order to study the influence of the initial velocity of tomato on weighing accuracy of yield monitor, a motion simulation model of yield monitor on tomato harvester was established. The tomato on the harvester was chosen for the research object. The analysis of motion process was completed by applying a method combined the motion theoretical analysis and motion simulation analysis. The results showed that in order to avoid the accuracy of the motion symmetry of tomato, tomato in the range of the load belt before entering the weighing belt is relatively static, and the initial movement speed of tomato from the color selected belt conveyor v₀ has a reasonable range: 0 mm/s≤v₀≤1 350 mm/s.