Abstract: The structure of beet top cutting device was designed according to cutting principle and standard of beet green top. The displacement equation of the profiler and the cutter were deduced,which proved theoretically that the top cutting device can realize the automatic adjustment of beet top cutting height. The virtual prototype of the top cutting device was established, and the influence of key parameters on the top cutting height of sugar beet were analyzed, such as the installation height, the installation angle of the cutter, the distance between the profiler and the cutter, the rod length, the spring stiffness, the cutting edge inclination angle, and the curve of the profiler. The structure and parameters of the beet top cutting device were optimized, and the beet top cutting experiment was carried out. The results showed that the device can realize the automatic adjustment of beet top cutting height and obtain the optimal value of beet top cutting height.