A study was conducted to establish a regression model of optimal fertilization for the ginseng under forest canopies by four-factor design of universal quadratic rotation combination. Analysis of main effect and single effect of the four factors showed that the yield increasing effect of nitrogen fertilizer was the best, followed by potassium fertilizer, compound micro-nutrient fertilizer, and potassium fertilizer. When the four kinds of fertilizers were used alone, the excessive dosage resulted in a decrease of yield. Response surface of the yield was drawn by means of the interaction effect of the four factors. The levels of the four fertilizers were calculated when reaching the maximum yield of ginseng according to multivariate extreme value theory. The fertilization scheme for the highest yield was obtained by statistical analysis of yield functions. A profit function of fertilizers was established. The optimum scheme of fertilization for the highest profit was obtained as urea 26.74 g/m2, superphosphate fertilizer 55.00 g/m2, potassium sulphate 43.69 g/m2, and compound micronutrient fertilizer 8.8 g/m . The optimum fertilization scheme for the highest yield is quite near to net return maximization. The phenomenon that the yield increases but the profit decreases under the optimum fertilization scheme for ginseng under forest canopies does not exist.%采用二次通用旋转组合试验设计,建立了林下参施肥模型.对4因素进行主效应及单因子效应分析,得到增产效应由大到小的顺序是氮肥、钾肥、复合微肥、磷肥.4种肥料单独施用时,用量过多均造成减产；对4因素进行交互效应分析,将产量绘制成响应曲面；根据多元函数极值理论,计算产量达最高时肥料的水平；统计分析产量函数得出最高产量施肥方案；通过建立肥料利润函数,解得纯收益最大时的施肥方案:尿素26.74 g·m-2,过磷酸钙55.00 g ·m-2,硫酸钾43.69 g ·m-2,复合微肥8.8 g·m-2；最高产量与纯收益最大时的施肥方案十分接近,说明改善林下参施肥条件没有增产不增收现象.
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