The traditional plough share-type cultivator shows characteristics that the soil particle size is larger after broken, the working parts can easily wrapped and has lower soil-broken rate during operation in heavy soil. And ridge distance of cultivator is not applicable for potato. The key component of driving-type potato cultivator was designed, and the structural parameters that affected the effect of soil-broken were concluded. The structure and working principle of the cultivator were illustrated, and the rotating monomer that made of soil-broken knife was theoretically analyzed. The factors that affected soil-broken rate were got. Regarding the folding corner and blade length of the soil-broken knife, knife-cylinder, forward speed and tillage depth as the experimental factors, regarding soil-broken rate as the experiment indicators. The test was taken in the College of Engineering, Northeast Agricultural University at the beginning of November, 2016, which was carried out in the room. The power was provided by generator and the tillage depth can be adjusted by actuating device. Experimental results showed that the machine had the soil-broken rate of 93.8%, when the knife-cylinder was 275r/min, the speed was 0.75m/s, blade folding corner was 150°, the length of the blade was 0.07m, and tillage depth was 0.18m. The optimal structural parameters of soil-broken knife were determined by experiment. And the experiment also verified the accuracy of theoretical formula. It was well conformed to the agronomic requirements of cultivator. The structure of soil-broken knife assembled on driving-type cultivator can enhance the cutting force to achieve better soil crushing effect. The machine basically solved the serious problems such as the lower efficiency of soil broken. It was more suitable for the tillage operation of potato when compared with the traditional cultivator. The study provided important theoretical and technical reference for the improvement and optimization of the driving-type potato cultivator.