Abstract: To explore the effect of different application amount of potash fertilizer on yield and quality of sweet potato and to search the best potash fertilizer level for sweet potato with high quality and high yield, experiments of six different application amount of potash fertilizer on‘Shangshu 19’in the east of Henan was conducted. Results showed that compared with check experiment, the five potash fertilizer experiments of B (75 kg/hm²), C (150 kg/hm²), D (225 kg/hm²), E (300 kg/hm²), F (450 kg/hm²) increased the fresh potato yield, from 5.1% to 22.0%; the dry slice potato, from 7.3% to 42.8%; commercial fresh potato, from 8.1% to 65.4%; dry-slice-yielding rate , form 0.5% to 4.2%; the rate of starch, from 0.44% to 3.66% and fresh stem and leaf decreased from 20.4% to 43.9%. And more potash fertilizer can effectively control sweet potato stem and leaf excessive growth, increase its yield and quality.