A field experiment in Randomized Complete Block Design was conducted to study the effects of different sources (potassium chloride and potassium sulfate) and rates of potassium fertilizer on potato yield and quality in order to guide the application of potassium fertilizer on potato, using 'Helan 15' as experimental material. The results indicated that potato yield was improved, and reducing sugar content was reduced by using different sources of potassium fertilizer. Tuber weight and yield were increased more by potassium chloride than potassium sulfate. 18 kg/667m2 (K2O) was the best when the potassium chloride was used, while 21 kg/667m2 (K2O) was the best when the potassium sulfate was used. In order to get high quality of potato, potassium chloride was superior to potassium sulfate when low rate of potassium fertilizer was used; however, potassium sulfate was superior to potassium chloride when high rate of potassium fertilizer was applied.