In the process of harvest, spinach plants could be damaged easily by clamping conveyer device. To solve the problem, the rheological property of spinach plants was used to analyze the gripping delivery parameters on the effect of damage to spinach. Firstly, a kind of spinach gripping delivery device was put forward, its working principle and the mechanical structure were expounded, the relationship of floating clamping device with spinach plants was analyzed. Rheological constitutive equation of spinach plants under the action of extrusion was constructed by Burgers viscoelastic model. By the creep test, the constitutive equation coefficients of spinach plant samples were obtained. Without considering elastic deformation and viscoplastic deformation, the constitutive equation of spinach plastic deformation was obtained and the degree of plastic deformation was used to measure spinach mechanical damage. The influence of equivalent modulus of elasticity, transmission speed on plastic deformation was researched. The operation condition of minimum plastic deformation was obtained and it could achieve low damage harvest at this time. Three kinds of transmission speed and three kinds of equivalent modulus of elasticity were selected, and the five groups of parameters were studied. The constitutive equation of clamping force with time under different working parameters was obtained, and the operation condition for minimum plastic deformation could be obtained by the equation. Finally, a gripping delivery test platform was set up, the result of the experiment showed that when the equivalent modulus of elasticity was 2N/mm, the transmission speed was 25mm/s, the success rate of conveying spinach was 93.3% and the injury rate of spinach was 6.7%, the effect of gripping delivery was better. The experiment proved that the rheological properties of the spinach could be used to analyze of the influence of working parameters on the spinach damage feasibility. The research provided the theoretical basis and technical reference for the design of the leafy vegetable low damage mechanical harvest.