A field experiment was carried out to study the effects of different types and rates of potassium fertilizer on growth and yield of sweet potato,potassium sulfate and potassium chloride were selected as test materials.The results showed that the applying of potassium fertilizer improved fresh weight of root tube per plant,increased yield of sweet potatoes and improved marketable tuber percentage,but there was no significant difference for the rate of dry root.Under the conditions of this test,both potassium sulfate and potassium chloride treatments had the maximum commodity yield(31 690.8 and 30 363.4 kg/hm2 )and fresh yield(33 439.7 and 32 740.4 kg/hm2) when applying K2O 135 kg/hm2.There was no obvious difference for the fresh yield between potassium sulfate treatment and potassium chloride treatment with K2O application of 90~135 kg/hm2.