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In order to settle the problems of loose spinach harvesting and large rootcutting resistance, starting from the characteristics of rootsoil composite, the interaction between spinach roots, soil and rootcutting shovel in the harvest process was analyzed to optimize root gathering, reduce soil clogging, reduce shovel cutting resistance, and improve spinach root cutting efficiency. Firstly, a new type of rootcutting shovel with both rootcutting and rootgathering functions was designed. A rootcutting force model was established to calculate and optimize the key parameters of the blade. The blade cutting angle was determined as 60°, and the blade angle was 45°; the biomechanical properties of spinach roots were measured, a discrete element model of spinach roots with flexible body was established, and the bonding parameters of spinach roots were calculated based on the constitutive equation of the particle contact model. The spinach rootsoil composite was established in combination with the soil model and the parameters of that were calibrated. A cutting simulation process of the rootsoil composite with rootcutting shovel was built to clarify the working mechanism of the rootcutting shovel, and the main parameters that affected the performance of rootcutting and rootgathering were determined. The response surface simulation design was used to optimize the parameters of the rootcutting shovel. The optimal design parameters of the rootcutting shovel were determined as follows: blade angle was 76°, blade length ratio was 57%, and shove groove area ratio was 40%. Field spinach harvesting test showed that the rootcutting average rate was 93.8%, and the harvesting average rate was 87.2%. This research can provide theoretical guidance for the development of spinach harvester. 