In the dry farming potato growing areas in southern Ningxia in 2019, field trials were conducted to study the effects of different potassium fertilizer dosages(0, 45, 90, 135, 180 kg/hm2) on potato dry matter accumulation, yield and water-fertilizer utilization efficiency with traditional and Fenlong tillage methods. The results showed that compared to traditional tillage methods, dry matter accumulation was significantly increased under Fenlong tillage, as the maximum dry matter accumulation rate and average dry matter accumulation rate increased 33.3% and 31.0%, respectively. The total amount of dry matter accumulation of potatoes treated with 90 kg/hm2 potassium fertilizer was significantly higher than those of other potassium fertilizer treatments. Under the uniform potassium fertilizer treatments, Fenlong tillage significantly increased individual plant mass, individual potato mass and commercial potato rate, and reduced the rate of small potatoes. Compared to traditional tillage, Fenlong tillage increased yield by 23.3%. Under Fenlong tillage, the potatoes with a 90 kg/hm2 potassium fertilizer yield reached 45 122.5 kg/hm2 at its highest. Under both tillage methods, potassium fertilizer utilization rate was highest with the 90 kg/hm2 potassium fertilizer treatment, reaching 46.0% and 55.0% for traditional and Fenlong tillage methods, respectively. Under the uniform potassium fertilizer treatments, water utilization efficiencies increased 29.7%-39.8% with Fenlong tillage compared to traditional tillage. We could conclude that Fenlong tillage combined with appropriate potassium fertilizer application significantly promote the potato growth, increase the potato yield and water-fertilizer utilization efficiency.