Aiming at the serious mechanical damage of potato tuber during the lifting process of potato excavator, through the kinematic analysis of potato lifting process and the energy analysis method of potato and bar collision process, through the establishment of the mathematical model of damage energy in the process of lifting and separating, the main factors influencing the mechanical damage of potato during the lifting process are the drop height, lifting chain speed and the angle of the lifting chain. At the same time, the range of test values of main factors is determined. Taking the damage comprehensive index and the injury rate of potato as the evaluation index, taking the drop height, the inclination angle of the secondary lifting chain and the linear speed of the secondary lifting chain as the experimental factors, the quadratic orthogonal rotation regression test was carried out. The regression mathematical model between each index and factor was established, and the influence rule of each factor on the evaluation index was analyzed. AccorIng to the regression model, the parameters were optimized. When the linear speed of the lifting chain is 1.42m/s, the Ip angle is 27° and the drop height is 220mm, the damage comprehensive index is 0.43, and the injury rate is 3.6%, which is significantly lower than the mechanical damage of potato block of potato excavator without parameter optimization, and meets the requirements of potato harvesting.