In order to solve the problems of high labor intensity, low efficiency and difficult separation of fruit and soil during dry harvesting of water chestnut, a vibration extrusion type water chestnut harvester was designed to improve the degree of separation of fruit and soil by enhancing the effect of soil fragmentation. The separated water chestnut was scattered on the surface for easy manual picking up. Through the stress analysis of water chestnut soil block in the process of operation, the key parameters affecting the separation performance are determined as vibration plate amplitude, vibration frequency of vibration plate and rotation speed of nail roller, and the value range of key parameters is preliminarily determined according to the existing experience. Taking the vibration amplitude of the vibration plate, the vibration frequency of the vibration plate and the rotation speed of the nail roller as the influencing factors, taking the soil layer breaking rate as the evaluation index, using Design-Expert 10.0 to design the CCD center combination test, and through the simulation of the RecurDyn-EDM coupling, it is determined that when the vibration frequency of the vibration extrusion plate is 33.045mm, the vibration frequency of the vibration plate is 6.631Hz, and the rotation speed of the nail roller is 336.721r/min Hz, there is a better breaking effect, and the soil layer breaking rate is 93.581%. The field verification test was carried out with the actual amplitude of vibration plate 32.41 mm, vibration frequency 6.5 Hz, and nail tooth rolling speed 330 r/min, and the results showed that the actual soil layer breaking rate was 93.546%, the Mingfa rate was 80.334%, and the damage rate was 28.088%. The soil breaking effect was good, and the fitting degree with the simulation results was high.