To reduce the losses of bruising and damage, an appropriate available potato-soil separation technology is essential during the potato harvesting process. Combined with the agronomic techniques of potato cultivation in the north of China, a potato harvester with double cushions at low position laying stage was designed, which was developed with the potato-soil-impurity separation technology of vibration separation, double cushions, and low position laying. The harvester was mainly composed of excavating device, soil loosening and depth limiting device, low position laying and separation device, 2-level vibration device, soil cutting and seedlings cutting device, double cushions, soil compacting and flatting device and other parts. The kinetic models were established at the low position laying stage, and structural parameters of primary components were determined. The potato-soil separation device was divided into vibration separation stages and low position laying separation stage with double cushions, to improve the harvesting efficiency and reduce the harvesting losses. The loosening and depth limiting device was improved to reduce the bruising and damage. Simultaneously, the soil compacting device could effectively prevent potatoes from being buried by soil again after being excavated and separated, which was conducive to picking up and improving the average exposing rate. By impact recording technology, the impact characteristics of potatoes were analyzed at low position laying segment. It was shown that by the test results, the productivity was 0.41hm2/h and 0.54hm2/h, the damage rate was 1.03% and 0.84%, and the bruising rate was 1.52% and 0.95% at harvesting speed of 0.88m/s and 1.16\m/s, respectively. It was noteworthy that the performance indexes met the relevant standards. The research result provided a reference for further study on reducing the potato-soil separation losses to minimum and the optimization and the improvement of separation technology.