In recent years, with rapid growth of potato planting area, potato has become the fourth largest food crop and the largest noncereal food. Potato plays an important role in solving the problem of food security in developing countries. In view of potato massive planting situation, it is very important to solve the problem of the use of potato haulm before the harvest. At the present stage in China, the main way of dealing with potato seedling or burning is using chemicals which leads to the increased burden on the environment. It is a waste of resources with vine abandoned or burned, as the potato vine is rich of nutrients, and do not meet the requirements of the sustainable development of agriculture in China. Cutting treatment of potato haulm before the potato harvest can not only reduce the potato harvesting machine failure rate and power consumption, but also very much conform to the agronomic requirements. Potato machinery cut haulms can make potato tuber skin aging that can make it easier separate from vine. After cutting haulms, potato tuber can significantly reduce the mechanical damage because of harvest, transport and storage. So that cutting seedlings before the potato harvest has a great role in promoting to improve the quality of potato and the potato harvest efficiency. Currently available machines for potato haulm cutting effect is not very ideal, and there are some problems such as poor breaking length qualified rate, high rate of tuber and soil severe adhesion in the shield, and so on. In order to solve the problems above, this paper presented a potato haulm cutter. This article described the main structure and working principle of the machine. The experiment was carried out with the combination design of orthogonal and quadratic regression equation for the flail. The influence factors of field experiment included rotational speed of knifecylinder, forward speed and distance between knife on ridge and ground. Evaluation indices included break length pass rate, stubble height and the potato carrying rate. The Design-Expert software was used to analyze and optimize the test results, and to obtain a better combination of factors. According with the comparison with the potato professional standard validation, the superiority of this haulm cutter was verified. Results indicated that: the performance of cutting haulm was improved because of the design of structure parameters of flail and the shield eccentric arc structure could reduce the soil adhesion. The field test showed that when rotational speed of knifecylinder was 1500~1600r/min, forward speed was 4.5~6.0km/h and distance between knife on ridge and ground was 50~52mm, break length pass rate was 94.7%~95.5%, stubble height was 56.0~59.9mm and the potato carrying rate was 0.15%~0.23%. The research provided a solution of the potato haulm cutter to soil adhesion serious, low breaking length, qualified rate and high stubble height after cut the haulm. The study provided a solution during cutting the potato haulm and provided the reference for further research of potato haulm cutter.