Abstract: In order to explore the high-yield and high-efficiency fertilizer and density cultivation scheme of Quandou 20 and accelerate the popularization and application of varieties, a four-factor（ full implementation ）with five-level quadratic general rotation combination design was used to study the effects of density（ X₁ ), nitrogen fertilizer（ X₂ ), phosphorus fertilizer（ X₃ ）and potassium fertilizer（ X₄ ）on the yield of Quandou 20. The quadratic regression mathematical model with the yield of Quandou 20 as the objective function was established to analyze the main effects and interaction effects of each factor on the yield. The results showed that: the quadratic regression mathematical model established in this experiment reached a very significant level, and the regression model had a good fit with the actual situation. The significance test results of regression coefficient showed that the first term of planting density was significant level, and the second term was extremely significant level. The quadratic terms of nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer were extremely significant ; the interaction effect of phosphate fertilizer and potassium fertilizer was significant. The order of influence of each factor on the yield of Quandou 20 was shown as follows: potassium fertilizer application rate ＞ planting density ＞ nitrogen fertilizer application rate ＞ phosphorus fertilizer application rate. According to the model, the optiomal fertilizer and desity combination scheme for a target yield of 2270.07 kg·hm⁻² was proposed for planting density of 24.31 × 10⁴～26.23 × 10⁴ plants·hm⁻², nitrogen fertilizer application rate of 78.42～91.59 kg·hm⁻², phosphorus fertilizer application rate of 252.60～311.10 kg·hm⁻², and potassium fertilizer application rate of 81.96～93.51 kg·hm⁻².