The work aims to propose a vibration isolation system for fruit and vegetable transportation based on geometric nonlinearity according to the theory of nonlinear vibration. Firstly, the vibration isolation structure for fruit and vegetable transportation was designed based on the parallel connection of the horizontal oblique negative stiffness spring and the vertical positive stiffness spring. Secondly, the static characteristics of the structure were analyzed and the stiffness characteristics were derived. Finally, the motion differential equation of the fruit and vegetable transportation vehicle was established, and the harmonic balance method was adopted. The results showed that through the reasonable design of structural parameters, the isolator could achieve high static stiffness and low dynamic stiffness near the equilibrium point. For small road excitation, the proposed system would perform much better than the corresponding linear system. With the increase of road excitation amplitude, the stiffness increased rapidly, the jump phenomenon appeared, the peak value gradually appeared and shifted to the right and the vibration isolation effect in medium frequency band got worse. The performance in high frequency was always far superior to the corresponding linear system, and it had little relationship with the road excitation amplitude. By introducing the geometric nonlinear structure of parallel connection of horizontal pre-compression spring and vertical spring, the vibration isolation effect of fruit and vegetable transportation vibration isolation system can be significantly improved, and the vibration and shock of fruits and vegetables during transportation can be reduced, so as to avoid damage and quality deterioration of fruits and vegetables.