Abstract: A field fertilization experiment of sweet potato was carried out in three main planting area of sweet potato of Jinjiang, Nanan and Huian by using ‘3414’ test program. The results showed that the contribution rate of soil basic fertility to quarterly output was 47.1%-88.8% with an average of 64.0%. And the nitrogen fertilizer had the best yield-increasing effect, followed by potassium fertilizer, and the fertilization effect of nitrogen phosphorus and potassium was N > K > P. The best yield of sweet potatoes in the test area could be obtained while the fertilization amounts per 667 m² were N 10.30-18.65 kg, P₂O₅ 3.00-6.62 kg, and K₂O 13.18-25.84 kg, and the average ratio of optimal fertilization of the three elements is N:P:K=1:0.28:1.23.