Blind fertilization and poor quality are common problems in walnut production.In order to clarify the effects of different fertilizer application on the quality of walnut and determine the appropriate amount of fertilizer to achieve high-quality walnut production，6-year-old ‘ Xiangling’was used as the test plant，the effects of nitrogen (N 0，0.25，0.50，0.75，1.25 kg·plant-1)，phosphorus(P2O5 0，0.10，0.20，0.40，0.80 kg·plant-1).and potassium.(K2O 0，0.15，0.30， 0.60，1.20 kg·plant-1)on two main quality indexes of walnut kernel，the protein and crude fat content，were studied under five fertilization levels.The results showed that nitrogen fertilizer and phosphorus fertilizer had no significant effects on the protein content of walnut kernel.The application of potassium fertilizer significantly affected the protein content of walnut kernel.With the increase of potassium fertilizer application rate，the protein content of walnut kernel increased first and then decreased，and the mathematical relationship conformed to the quadratic function equation y = -5.2872x2 + 4.2009x + 19.27(0.001