Abstract: Abstract: The blueberry belongs to small berry. Mechanical harvesting is the most effective way, but the falling and collision of the blueberries cannot be avoided. As a result the quality of the blueberries cannot be guaranteed. Even though the appearance of the fruit has not any obvious change, the inner of the fruit may be injured. In order to reduce the collision injury degree of the fruit in the process of harvesting, the collision characteristics of the blueberry fruit are researched based on the principle of the fruit energy balance. The highbush blueberry fruit is seriously damaged during mechanical harvesting, so it is selected to be analyzed. The geometric and mechanical parameters are obtained by measurement. The quasi static compression test of the fruit is conducted, and the compression deformation energy is analyzed. The deformation energy makes the fruit injured. An evaluation method of blueberry injury degree is proposed, and the injury degree can be determined according to the quantity of the deformation energy. The mechanical injury evaluation criterion of the fruit is obtained. The kinematics analysis of the fruit in the process of falling and collision is conducted based on the principle of mechanical harvesting. The maximum mechanical energy loss happens in the process of the first collision, which is transformed into the deformation energy. The equation of mechanical energy loss is obtained. The influence factors on the mechanical energy loss are the tilt angle of collecting plate of the harvester, the falling height and the mass of the fruit. The contact and collision between the collecting plate and the fruit is analyzed based on the Hertz theory. The deformation calculation is carried out, and the deformation of the fruit at normal direction can be obtained. Once the deformation value of the fruit is determined, the deformation energy can be determined. An orthogonal test scheme of fruit collision is designed. Three test factors, i.e. the tilt angle of collecting plate, the falling height and the mass of the fruit, are selected. Each factor has 3 levels. The finite element model of the blueberry fruit is established. Through the collision simulation with the model, the stress and strain data of the contact area are obtained. According to the deformation calculation equation, the theoretical values of collision deformation are acquired. And the theoretical values of the deformation energy are obtained. The sequence of the influence factors from high to low is the falling height, the title angle of the collecting plate and the mass of the fruit. To verify the correctness of the analysis result, a falling and collision test-bed of the blueberry is established. The collision test parameters are designed, through which the deformation energy values are obtained. The deformation energy values are nearly consistent with the theoretical values. The error between them is 0.49?10?3 J. The correctness and feasibility of the analysis of blueberry collision injury based on the energy method are verified. The installation and use parameters of the blueberry harvester are obtained. When the harvester satisfies the condition that the fruit concentration area of the blueberry tree is 600 mm from the collecting plate and the tilt angle of collecting plate is 15°, the deformation energy is less then 0.68?10?3 J and the number of fruit injured is the least. The research results have certain guiding significance and reference value for the design and use of the harvesting device of the blueberry harvesters.